GB2530968A

GB2530968A - Pneumatic calibration device

Info

Publication number: GB2530968A
Application number: GB1405764.0A
Authority: GB
Inventors: Ratner Cary
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-03-31
Filing date: 2014-03-31
Publication date: 2016-04-13
Also published as: GB201405764D0

Abstract

The invention relates to a pneumatic calibration device, effectively a hand-held pump for providing a controllable pressure for testing and calibrating pressure gauges, pressure switches or pressure transmitters. The invention comprises: a pump (102) for pressurising a chamber, an adjustment means (104) for adjusting the pressure in the chamber, a test device connector to connect the test device to the chamber, a pressure gauge connector to connect the pressure gauge to the chamber, characterised in that the pump comprises a pump body (106) and a pump lever (108), moveable relative to the body to operate the pump and the pump body is arranged to be supported against a planar surface in use.

Description

PNEUMATIC CALIBRATION DEVICE

The present invention relates to a pneumatic calibration device for providing a S controllable pressure to a test device. In particular, the present invention relates to a pneumatic calibration device for testing, calibrating and adjusting pressure gauges, pressure switches and pressure transmitters.

A pneumatic cahbration device provides an accurately controllabk pressure in order to calibrate a test device such as a pressure gauge, switch or transmitter. In order to generate a pressure within the pneumatic calibration device a hand operated pump is typically provided. The pump is activated by the user gripping and squeezing a pair of handles together. An example of such a prior art calibration device can be seen in patent GB 2 451 146. Such a pneumatic calibration device can be cumbersome and difficult to operate, and the pressure generated is limited by the squeezing action that the user is able to apply to the pair of handles.

The present invention provides a pneumatic calibration device, for providing a controllable pressure to a test device, comprising: a pump for pressurising a gas in a chamber; an adjustment mechanism arranged to adjust the pressure in the chamber a test device connector arranged to connect the test device to the chamber; and a pressure gauge connector arranged to connect a pressure gauge to the chamber, wherein the pump comprises a pump body and a pump lever movable relative to the pump body to operate the pump, the pump body being arranged to be supported against a planar surface during use, By allowing the pump body to be securely supported on a planar surface, the pump lever can be operated against the ground, a work bench or a wall. By supporting the pump body during use in this way a greater force can be consistenfly, efficiently and quickly applied by the user to generate pressure in the chamber, Furthermore, by resting the pump body on a surface such as the ground or work bench it is supported during use and the weight of the pump does not have to be supported by the user. The user's hands are therefore free to perform other functions such as connecting a test device, adjusting the pressure, reading a gauge attached to the pump or making modifications to the test device. This allows the pneumatic calibration device to be more conveniently and effectiv&y operated.

Optionally, the pump comprises at least one support leg pivotally attached to the pump S body. This provides a stable platform to support the pump body and hdps keep it stable during operation of the pump lever, Optionally, the at least one support leg may be movable between a stowed position and a deployed position. In the stowed position the support leg is located close to the pump body, therefore making the pneumatic calibration device small and easy to transport, Optionally, when the support kg is in the deployed position, the pump body has a greater footprint than when the support leg is in the stowed position (i.e, the deployed position of the at least one support leg provides the pump body a greater footprint compared to the stowed position of the at least one support leg). Tn the deployed position, the at least one support leg provides a arge p'atform on which the pneumatic calibration device can securely rest, This helps to stabilise the pneumatic calibration device during operation of the pump lever, Optionally, the at least one support kg i'nay comprise at least one foot member arranged to support the pump against the planar surface. The foot member helps provide a frictional engagement with the planar surface and helps the support leg grip the surface and reduces the risk of the pneumatic calibration device sliding on the planar surface during operation of the pump lever, Optionally, the pump body may comprise at least one foot member arranged to support the pump against the planar surface. The pump body may also have a foot member to help support the pump body and improve the stability of the pneumatic calibration device, Optionally, the at least one foot member may be located at, or near, any one or more of: an end of the pump body spaced away from a joint between the pump body and the pump lever; a point adjacent to a joint between the pump body and pump lever; and a point adjacent to a joint between the leg member and the pump body, Positioning the foot member at one or each of these positions improves the stability of the pneumatic cahbration device during operation of the pump ever, Optionally, the pump lever may comprise a foot engagement portion. The foot S engagement portion may be arranged to receive pressure applied by a user's foot. This allows thc pump lever to bc foot operated. If it is to be foot operated, the pneumatic calibration device is placed on the ground and the pump lever operated by the user's foot. Foot operation enables provision of a grcater force to the pump lever and can therefore increase the amount of pressure that can be delivered quickly by the pump.

Furthermore, by operating the pump by foot, the user's hands are free to perform other functions such as adjusting the pressure via thc adjustment mechanism or making adjustments to the test device that is being calibrated.

Optionally, the pump lever may further comprise a handle to be gripped by the user, the handle preferably bcing towards a distal end of the pump lever. This allows the pump lever to be hand operated. When operated by hand, the pneumatic calibration device may be rested on a workbench and the lever operated by hand, Afternativ&y, the pneumatic calibration device may be pressed against a wall in order to operate the lever by hand. By providing a grip at the distal end of the pump lever, the force applied by the operator is increased. In combination with resting against a surface, a longer hand operated ever can be provided, which aHows a greater torque to be applied by the pump lever.

Optionally, the calibration device may further comprise a locking mechanism arranged to selectively secure the pump lever to the pump body in a locked position. In some embodiments, the locking member may be attached to the pump body, By securing the pump lever in a locked position close to the pump body the overall size of the pneumatic calibration device is reduced and it is therefore more easily transported.

Optionally, the ocking mechanism may comprise a lock member arranged to engage an aperture in the lever, the lock member being movable between a first position in which it can pass through the aperture, and a second position in which it cannot pass through the aperture, such that the pump ever is secured in the ocked position by moving the lock member to the second position, This aflows the user to push the lever and pump body together and then move the locking member to a position in which it prevents the pump lever from moving away from the pump body. This fixes the pump lever in a convenient position to transport the pneumatic calibration device.

Optionally, the pump may comprise a first pumping stage and a second pumping stage.

S By providing two pumping stages, the pneumatic calibration device can provide a pressure over a greater range, It may also therefore provide a greater maximum pressure -Optionally, the combined first and second pumping stages may be arranged to produce a pressure in the chamber between approximately 14 PSI and 5000 PSI. This provides a suitably large pressure range to allow the calibration of a wide variety of test devices.

Optionally, the test device connector, the pressure gauge connector or both may extend from the pump body, and wherein none of the connectors extending from the pump body extend in a direction of the movement of the pump lever towards the pump body during operation of the pump, This means that the connectors do not extend in a direction towards the planar surface, thus allowing the connectors to be easily accessed and anything connected to the connectors does not prevent the pneumatic calibration device from resting securely on the planar surface.

Optionally, at least one or both of the adjustment mechanism and pressure gauge connector may extend from the pump body in a direction perpendicular to a plane in which the pnmp lever moves during operation of the pump. This aflows easy access to the connectors and means that the adjustment mechanism and a connected pressure gauge do not prevent the pneumatic calibration device from resting on the planar surface.

Optionally, the pneumatic calibration device may comprise a remote control member in fluid communication with the pump via a tube, wherein any one or more of the adjustment mechanism, pressure gauge connector and test device connector are provided on the remote control member. The remote control member allows the pump body to be located reniotdy from the adjustment mechanism, pressure gauge connector and/or test device, Optionally, the flexible tube may have a length between 5 ft (about 1.5 m) and 10 ft (about 3 rn). This aflows the pump body to be p'aced on the ground and operated by foot, whilst the remote control member can be hand operated and located in a convenient position to operate the adjustment mechanism, read the pressure gauge and connect the test device.

Optionally, the adjustment mechanism may comprise an adjustment member arranged to alter the volume of the chamber. thereby adjusting the pressure in the chamber.

This allows the pressure in the chamber to be precisely controlled and aflows the pneumatic calibration device to provide an accurately controlled pressure to the device under test.

Optionally, the pump may be foot operated. Foot operation of the pump provides a greater force to the pump lever than hand operation, and allows the pump to be operated whilst the user's hands are free to perform other functions.

In another aspect, the present invention provides a pneumatic calibration device for providing a controllable pressure to a test device being calibrated, comprising: a pump for pressurising gas in a chamber; an adjustment mechanism arranged to adjust the pressure in the chamber; a test device connector arranged to connect the test device to the chamber; and a pressure gauge connector arranged to connect a pressure gauge to the chamber, wherein the pump is arranged to be foot operated.

In another aspect. the present invention provides pneumatic calibration device for providing a controllable pressure to a test device, comprising: a pump for pressurising gas in a chamber; an adjustment mechanism arranged to adjust the pressure in the chamber; a test device connector arranged to connect the test device to the chamber; and a pressure gauge connector arranged to connect a pressure gauge to the chamber, wherein the pump comprises a first pumping stage arranged to provide a first pressure in the chamber and a second pumping stage arranged to provide a second pressure in the chamber, wherein the second pressure is greater than the first.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

D

Figure la shows a side view of a pneumatic calibration device having a foot operated pump lever according to a first embodiment, with its support legs deployed and its pump levcr unlocked; Figure lb shows a second side view of the pneumatic calibration device of Figure la, with the pump lever in the locked position and the support legs stowed; Figure 2a shows a top view of the pneumatic calibration device of Figure lb with its support legs stowed; Figure 2b shows a second side view of the pneumatic calibration device of Figure Ia with its support legs deployed; Figure 3a shows a side view of a pneumatic calibration device having a hand opcratcd pump levcr according to a second embodiment; Figure 3b shows a top view of the pneumatic calibration device of Figure 3a; Figure 4 shows a projection view of the pneumatic calibration device of Figure 3b with its support legs stowed; Figure 5 shows a second projection view of the pneumatic calibration of Figure 4, with its support legs deployed; Figure 6 shows views of a first embodiment of a remote contr& member for use with the pneumatic calibration device; Figure 7 shows views of a second embodiment of a remote contr& member for use with the pneumatic calibration device; Figure 8 shows a two-stage pump mechanism of a pneumatic calibration device according to the invention; and Figure 9 shows an adjustment mechanism for use with the pneumatic cahbration device according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of a calibration device 100 is shown in Figures I a, I b, 2a and 2b, In this embodiment the calibration device is adapted to be foot operated. Referring to Figures la, lb. 2a and 2b. a pneumatic calibration device 100 comprises a pump 102 for pressurising a gas (wherever the term air' is used in this specification, the skilled person will understand that any other suitable gas may be used instead) in a chamber; an adjustment mechanism 104 arranged to adjust the pressure in the chamber; a test device connector arranged to connect the test device to the chamber; and a pressure gauge connector arranged to connect a pressure gauge to the chamber. The pump 102 comprises a pump body 106 and a pump kver 108 movable relative to the pump body 106 to operate the pump 102, the pump body being arranged to be supported against a planar surface 101 during use.

The pump body 106 is generally cylindrical in shape in this embodiment, with the pump lever 108 pivotally attached towards one end. The pump body 106 comprises a housing which contains the pump 102, the chamber and the adjustment mechanism 104. The pressure gauge connector and test device connector are also provided on the housing such that they can be connected in fluid communication with the chamber, A test device can therefore be connected to the chamber via the test device connector. A pressure gauge can be connected to the chamber via the pressure gauge connector.

The chamber is arranged to receive pressurised air from the pump. The pressure in the chamber is arranged to be communicated to a test device connected via the test device connector. The pressure is also arranged to be communicated to a pressure gauge via the pressure gauge connector. The test device connector and pressure gauge connector may be a valve or other suitable connection means.

The adjustment mechanism 104 comprises an adjustment member arranged to alter the volume of the chamber, thereby adj usting the pressure in the chamber. The adj ustment mechanism 104 can be operated to make small adjustments to the volume of the chamber and therefore, the pressure in the chamber.

The pump lever I 08 is pivotally attached to the pump body 106 by a linkage 109 at a S pivot point. The pump is actuated by the pump lever 108 when it is pushed or pulled in an arc about the pivot point.

The linkage 109 may be a four bar linkage arranged to amplify the force exerted on the pump lever 108 by the user. The four bar linkage may provide a ratio of 21:1 between the force applied to the pump lever 108 by the user and the force applied at the pump mechanism, The linkage 109 has a further advantage of amplifying the force delivered in the phase of the pump lever's 108 movement when it is closest to the pump body 106. This provides the greatest amplification of force when the pressure in the pump will be at its highest and allows the user to more easily overcome the resistance of the pump. In some embodiments an alternative linkage may be used to connect the pump lever 108 to the pump body 106. Tn other embodiments the ratio of force applied to the pump lever 108 by the user and the force applied at the pump mechanism may be different. In some embodiments the pump lever may be pivotally connected to the pump body at the pivot point with no additional linkage provided, The pneumatic calibration device 100 comprises at least one support leg I 12 pivotally attached to the pump body 106. In the embodiment of Figures la, lb. 2a and 2b the pneumatic calibration device 100 comprises a pair of support legs 1 12a, 1 12b. The pair of support legs 112a, I 12b pivot symmetrically outwards from the pump body 106, The support legs 1 12a, 1 12b are movable between a stowed position (as shown in Figure 2a) and a deployed position (as shown in Figure 2b). In the stowed position, the support legs 1 12a. 1 12b lie flat against the pump body 106 such that the overall size of the pneumatic calibration device 100 is reduced to allow easy transport and storage. From the stowed position. the support legs may be folded out in a deployed position. When at least one of the support legs is in the deployed position, the pump body has a greater footprint than when the support is in the stowed position. This means that the deployed position provides the pump body 106 a greater footprint compared to the stowed position of the at least one support leg. The increased footprint of the deployed position increases the surface area over which the pneumatic calibration device 100 is supported by the planar surface 101. This improves the stability of the device and reduces the chances of it slipping or falling over when the pump lever 108 is operated, or the user's hand or foot slipping during operation of the hump S The support legs II 2a, II 2b further comprise at least one foot member 11 4a, 11 4b arranged to support the pump against the planar surface 101, In the embodiment of Figures Ia. lb. 2a and 2b there are two foot members 1 14a. 1 14b each positioned at a distal end of each of the support legs 1 12a, 1 12b. The foot members 1 14a, 1 14b allow the support legs 11 2a. 11 2b to grip the p'anar surface 101 to improve the stability of the pneumatic calibration device 100 during operation of the pump lever 108. The foot members 1 14a, 1 14b may comprise a rubber material that provides a frictional engagement with the planar surface 101 to reduce risk of the pneumatic calibration device 100 shding on the planar surface 101 during use.

In this embodiment. the pump body 106 also comprises a foot member 1 14c arranged to support the pump body 106 against the p'anar surface 101. In this embodiment, the foot member I 14c may be located near a point at the end of the body 106 adjacent to a joint between the pump body 106 and the pump lever 108. In other embodiments, the foot member 114c may be located at or near an end of the pump body 106 spaced away from a joint between the pump body 106 and the pump lever 108. In yet other embodiments, the foot member I 14c may be located at or near a point adjacent to a joint between the leg member 1 12a. 1 12b and the pump body 106. In other embodiments the pump body may comprise one or more foot members at any one or more of the positions mentioned above. In other embodiments, there may be no foot members provided at the pump body 106, in which case the pump body 106 is adequately supported by the foot members provided on the support legs 1 12a, 1 12b.

As can be seen in Figures Ia. ib, 2a and 2b the foot members 114a, 114b, 114c are located within a plane against which the pump body 106 is supported against the planar surface 101. The foot members I I 4a. I I 4b. I I 4c therefore provide a secure support means with which the pump body 106 can be pressed against the planar surface 101 during operation of the pump lever 108. This allows the pneumatic cahbration device 100 to be p'aced upon a surface snch as the ground and operated by foot. or rested on a work bench and operated by hand, During operation the user is therefore not required to support the device, and is able to more conveniently operate the adjustment mechanism and connect or operate the device under test.

In sonic embodiments, the foot members 11 4a. I I 4b, I I 4c space the pump body from S the planar surface 101 in order to allow clearance for other components (such as a pressure gauge) to be connected whilst still allowing the support member to rest on the planar surface 101. This allows the pump body to be securely supported by the planar surface without interfering with the connection to other components.

In order to facilitate convenient foot operation, the pump lever 108 comprises a foot engagement portion 116. The foot engagement portion 116 is arranged to receive pressure applied by a user's foot. In this embodiment, the lever 106 increases in width such that it is tapered in a direction moving away from the joint with the pump body 106. The foot engagement portion 116 is located at a point towards the distal end of the lever 108 and provides a flat plate portion which the user may press on to apply pressure with their foot.

The pump lever 108 further comprises a handle 118 formed by an aperture in the foot engagement portion 116. The user is able to operate the lever by pressing the foot engagement portion 116 using their foot or, alternatively, by gripping the handle 118 with their hand.

In this embodiment, the pneumatic calibration device 100 further comprises a locking mechanism 120, In some embodiments, the locking member 120 is attached to the pump body 106. In other embodiments, the locking member is attached to the pump lever 108. The locking member 120 is arranged to secure the pump lever 108 to the pump body in a locked position when not in use. In the locked position, the locking mechanism 120 secures the pump lever 108 such that it lies close to the pump body 106, therefore reducing the overall size of the pneumatic calibration device I 00. This allows the pneumatic calibration device 100 to be easily stored and transported. When the pump leverlO8 is to be operated, the locking mechanism 120 is disengaged so that the pump lever 108 is free to move about the pivot point.

The locking mechanism 120 comprises a lock member arranged to engage an aperture 122 in the pump lever 108, The lock member is movable between a first position in which it can pass through the aperture 122, and a second position in which it cannot pass through the aperture 122. Tn sonic embodiments, the ock member rotates about a pivot point between the first and second positions. When the lock member is in the first position, the pump lever I 08 can be moved into the locked position in which it is S folded close to the pump body 106, Once in the locked position, the lock member is rotatcd into the second position. in which it engages with the pump lever 108, thus securing the pump lever 108 in the locked position. By rotating the lock member 120 back to the first position thc lever is released from the locked position and can be operated by the user. In other embodiments, the locking member is attached to the pump lever 108 and is arranged to engage with an aperture provided at the pump body The test device connector and the pressure gauge connector are located on the pump body so that they can be easily accessed during use and do not prevent the pump body from resting on the planar surface. The test device connector, the pressure gauge connector or both are therefore arranged to extend from the pump body 106 such that none of the connectors extend from the pump body 106 in a direction of the movement of the pump lever 108 towards the pump body 106 during operation of the pump. This means that none of the connectors extend in a direction away from the pump body 106 and towards the planar surface 101 on which the pump body 106 is arranged to rest when in use. By locating the connectors away from this direction, access to them is not blocked by the planar surface 101, and the pneumatic calibration device 100 can be conveniently rested on the planar surface 101 without interference from the test device or the pressure gauge connection, Furthermore, by ocating the connectors away from a direction towards the planar surface, the foot members 112a. 1 12b are not required to be of sufficient height to space the pump body 106 from the planar surface 101 to an extent that access is provided to the connectors. This therefore reduces the height of the foot members 1 12a, 1 12b and improves the stability of the pneumatic cahbration device.

In other embodiments, one or more of the test device connector, the pressure gauge connector or both are arranged to extend from the pump body 106 in a direction of the movement of the pump lever 108 towards the pump body during operation of the pump. In such an embodiment, the foot members I 14a, I 14b 11 4c have a height such that the pump body is spaced from the planar surface 101 in order for the connectors to be accessed whilst the pump body 106 is supported on the p'anar surface 101 In some embodiments, at least one or both of the adjustment mechanism 104 and the S pressure gauge connector extend from the pump body 106 in a direction perpendicular to a plane in which the pump lever 108 moves during operation of the pump. The pressure gauge connector and the adj ustment mechanism therefore extend away from thc pump body in a dircction away from the planar surface 101. This ensures that they can be easfly accessed when the pneumatic calibration device 100 is resting on the planar surface 101. In the embodiment shown in Figures 1 to 5. the adjustment mechanism 104 is located such that it extends from the pump body in a direction away from the planar surface, and is therefore easily accessed by the user.

The first embodiment of the calibration pump shown in Figures la, ib, 2a and 2b is intended to be foot operated. In the second embodiment. shown in Figures 3a, 3b. 4 and 5. the pneumatic cahbration device 200 is intended to be hand operated. The pneumatic calibration device 100 of the second embodiment shares the same features as that of the first embodiment, with the following modifications so that it is adapted for hand operation.

As shown in Figures 3a. 3b, 4 and 5, the lever 108 is adapted for hand operation and is therefore generally an extended cylindrical shape such that it may be gripped by the user. A grip 110 is provided at a distal end of the lever 108 such that it may more easfly be gripped by the user. The hand operated pump lever 108 of the second embodiment provides a long lever that can be operated against the planar surface 101, The provision of a long lever increases the torque that can be generated by the lever and therefore increases the force that can be applied at the pump mechanism. This increases the range of pressure that can be generated by the pump.

Despite not being shown in Figures 3a, 3b, 4 and 5, the pneumatic calibration pump of the second embodiment may also comprise a locking mechanism arranged to lock the pump lever in a locked position when it is not in use.

In some embodiments, as shown in Figures 6 and 7, the pneumatic calibration device 100 comprises a remote control member 200 in fluid communication with the pump via a tube 202. The remote control member 200 can be used with either the foot operated pneumatic calibration device of the first embodiment, or the hand operated calibration device of the second embodiment. The tube 202 may be a flexible tube, such as a flexibk pressure hose. The remote control member comprises a housing S which contains the chamber in which pressure is applied from the pump via the tube.

In the embodiment shown in Figures 7 and 8 the adjustment mechanism 104, the pressure gauge connector and the test device connector are also provided on the rcmotc control mcmbcr 200. In some embodiments, the adjustmcnt mcchanism 104 and the chamber are provided at the pump body 106, whilst the test device connector and the pressure gauge connector are provided at the remote control member 200. The pressure device connector is attachcd to the test dcvicc via a sccond tube 204. In the embodiment shown in Figure 6, the test device connection tube 204 extends from the housing adjacent, and in the same direction, as the tube 202. In the embodiment shown in Figure 7. the test device connection tube 204 extends from the housing in a direction opposite the tube 202. This allows the test device connection to be more easfly accessed whdst the user is holding the remote contro' member and allows the test device to be more easily connected.

In some embodiments, any one or more of the adjustment mechanism 104, the pressure gauge connector and the test device connector are provided on the remote control member 200, with the others provided on the pump body 106. In Figures 6 and 7, the pressure gauge connector is shown connected to the pressure gauge 206. In this embodiment. the remote control member 200 also provides a pressure release control 208. The remote control member 200 aflows the pump to be ocated away from the adjustment mechanism 104, the pressure gauge connector and the test device connector. The pump body 106 may therefore be placed on the planar surface 101, whilst the remote control member is held by the user in a convenient position to connect it to the device under test, see the gauge clearly and adjust the pressure using the adjustment mechanism 104. In some embodiments, the tube has a length of between 1.5 m and 3 iii, such that the pump body 106 can be placed on the ground and the remote control member 200 held at a convenient height by the user, in other embodiments the connection tube 204 may have a length of greater than 3 m so that the pump can be connected at a greater distance from the test device, in other embodiments, the connection tube 204 may have a ength less than 1.5 m so as to reduce the distance over which pressurised air must travel from the pump to the control member. In other embodiments the tube may have a length between 0.1 in and 1.5 m such that the pump body can be placed on a bench and operated by hand, The pump mechanism is shown in more detail in Figure 8, In order to provide a high cahbration pressure, the pump comprises a first pumping stage A (i.e. cylinder #1, stage #1) and a second pumping stage B (i.e. cylinder #2, stage #2). The first stage is arranged to compress gas for the second stage. Preferable dimensions are shown in Figure 8. however tile skilled person will understand that other dimensions can be used as is appropriate. The first pumping stage comprises a first pump cylinder 302, which is activated via a first shaft 303 attached to the pump handle 208, In the embodiment shown in Figure 8, the first cylinder 302 has an inner diameter of approximately 43 mm. a stroke depth of approximately 50 mm and is able to generate a pressure from 1.4 to 180,0 PSI. In other embodiments the first cyhnder may have an inner diameter of approximately 1 inch (about 25 mm) with a stroke depth of approximately 3 inches (about 80 mm) in order to provide an output pressure of approximately 200 PSI. The second pumping stage comprises a second pump cylinder 304, The second pump cylinder 304 is attached to the first pump cylinder 302 via a non-return valve 306, The second cylinder is actuated by a second shaft 308, which is connected to the first shaft 303 such that both cylinders are activated at the same time by movement of thc pump lever 208. In this embodiment. thc intcrnai diameter of the second pump cylinder is approximately 10 i'nm, The second cylinder 304 is arranged to producc a prcssure from 180 PSI up to 4500-5000 PSI. In some embodiments the pressure provided by the pump may be greater than 5000 PSI.

The internal diameter of the second pump cylinder 304 is less than the first pump cylinder 302 such that the second pumping stage is arranged to produce a greater pressure than the first. In some embodiments the ratio between the sccond pump 304 cylinder internai diameter and that of the first pump cylinder 302 may be 4.1. In other embodiments, the ratio may be different, e.g. it may be greater in other embodiments, and lower in yet other embodiments. e.g. it may be 5:1, By providing a foot operated pneumatic calibration pump (or a hand operated pump with a long pump lever 108) in combination with a two stage pump. a greater pressure range can be achieved. In the case of a prior art calibration device operated by squeezing a pair of handles, the force that can be generated by the pump lever is limited by the short handles and the strength of the user required to squeeze the handks together. Such a pump lever is therefore more suitabk for use in combination with a single stage pump, which has a limited pressure output. The pneumatic cahbration pump of the present invention allows a greater force to be produced by the lever, which in turn can be used to operate a two stage pump mechanism and provide a greater range of output pressure.

The output of the second pump cylinder 304 is connected to a spool valve 312 via a pair of non-return valves 310. The spoo' valve 312 comprises a vent 3 14 at which ambient air may enter or leave the pump system. The spool valve allows the pump to produce either a pressure greater than atmospheric pressure, or a pressure less than atmospheric pressure (i.e. a vacuum). The spool valve is also connected to a reservoir 316 (the reservoir 316 may be a high pressure or a vacuum reservoir). In this embodiment, the adjustment mechanism is provided at the reservoir and is therefore operable to adjust the volume of the reservoir and adjust the pressure. The output of the reservoir 316 is connected via a tube 202 and an is&ation va've 318 to two test device connectors 320a, 320b. The tube 202 is &so connected to a pressure release valve 208 (e.g. a dump or bleed valve).

In some embodinients the adj ustment mechanism 104 may comprise the adj ustment mechanism 400 shown in Figure 9, The adjustment mechanism 400 shown in Figure 9 can be used in conjunction with the first and second embodiments described above and alternatively can be provided at the remote control member 200 shown in Figures 6 and 7.

The control mechanism 400 comprises a main body 420 having a central bore 421 in which is provided a piston 422 slidablc within the bore 421. The piston 422 has a narrow neck 424 defining a central passageway 425 that is in communication with the chamber, the neck 424 broadening out to define a bore 426 housing a shaft 423 that is slidable relative to the walls of the piston 422. The shaft 423 has a V-shaped end 427 that abuts a ball 428 that is trapped between the end 427 of the shaft 423 and the end of neck 424. In a wall of the piston 422 there is provided a passageway 432 that connects passageway 425 to a reservoir (not shown). In one condition the baIl 428 seals passageway 432 and the chamber 433 from passageway 425 and in another condition the passagewavs 432 and 425 arc in fluidic communication, The adjustment mechanism 400 further comprises an adjustment control knob 429 having at one end a screw thread that engages with a complimentary screw thread on the main body 420 with the other end 484 of a knob 429 comprising a flattened oop S that defines a square shaped cavity 450, The knob 429 further comprises an inner annular abutment 431 that engages with an outer annular projection 462 on the piston 422 to regulate the extent of movement of the piston 422 out from the main body 420.

Connected to an end of the shaft 423 is a release contr& knob 434. The knob 434 is arranged to extend from knob 429 so as to be located in cavity 450 defined by the end of knob 429, In this embodiment, knob 434 is located so as to be concentric with knob 429 (i.e. located around a common centre). By this arrangement, the user can operate both contr& knobs 439, 434 with the same hand. Furthermore, end 484 of knob 429 protects knob 434 from impacts that could cause damage to the pump, such as breaking of shaft 423.

In use, the piston 422 can be caused to shde inwardly and outwardly of the main body 420 by adjusting the knob 429 thereby varying the volume defined by the passageway 425 and the central bore of the main body 420, In the event that the user wishes to release the pressure in chamber, the user can pull knob 434 outwardly, moving shaft 423 away from the neck of the piston 422, allowing the ball 428 to move under the air pressure in the chamber away from passageway 432 such that air in the chamber is released to a reservoir or through a vent via the passageways 425 and 432.

Various modifications will be apparent to the skilled person without departing from the scope of the claims. The calibration device may be arranged to provide either a test pressure, or test vacuum. Using the pump mechanism shown in Figure 8. the calibration pump may provide a vacuum of 14.2 PSI. The pressure operation may be switched from pressure to vacuum via the spool valve 312, The spool valve disconnects the second pump stage, as only the first pump stage is required to produce the vacuum operation. The vacuum operation is provided by pulling the pump lever 108 upwards, in a direction away from the pump body 106.

Claims

CLAIM S1 A pneumatic calibration device, for providing a controllable pressure to a test device, comprising: S a pump for pressurising gas in a chamber; an adjustment mechanism arranged to adjust the pressure in the chanib e r; a test device connector arranged to connect the test device to the chamber; and a pressure gauge connector arranged to connect a pressure gauge to the chamber.wherein the pump comprises a pump body and a pump lever movable rdative to the pump body to operate the pump. the pump body being arranged to be supported against a planar surface during use.
2. A pneumatic cahbration device according to claim I, wherein the pump comprises at least one support leg pivotafly attached to the pump body.
3. A pncumatic calibration dcvice according to claim 2, wherein the at least one support leg is movable between a stowed position and a deployed position.
4. A pneumatic calibration device according to claim 3. wherein when the support leg is in the deployed position, the pump body has a greater footprint than when the support kg is in the stowed position.
5. A pneumatic calibration device according to any one or more of claims 2 to 4, wherein the at least one support leg comprises at least one foot member arranged to support the pump against the planar surface.
6, A pneumatic calibration device according to any preceding claim, wherein the pump body comprises at least one foot member arranged to support the pump against the planar surface.
7, A pneumatic calibration device according to claim 6. wherein the at east one foot member is located at, or near, any one or more of: an end of the pump body spaced away from aj oint between the pump body and the pump lever; a point adjacent to a joint between the pump body and pump lever; and a point adjacent to a joint between the leg member and the pump body.
8, A pneumatic calibration dcvice according to any preceding claim, wherein the pump lever comprises a foot engagement portion.
9, A pneumatic calibration device according to any preceding claim, wherein the pump lever further comprises a handle to be gripped by the user, the handle preferably being towards a distal end of the pump lever.
10. A pneumatic calibration device according to any preceding claim, further comprising a locking mechanism arranged to selectively secure the pump lever to the pump body in a locked position.
11. A pneumatic calibration device according to claim 10, wherein the locking mechanism comprises a lock member arranged to engage an aperture in the lever, thc lock mcmbcr bcing movable between a first position in which it can pass through the aperture, and a second position in which it cannot pass through the aperture, such that the pump lever is secured in the locked position by moving the lock member to the second position.
12. A pneumatic calibration device according to any preceding claim, wherein the pump comprises a first pumping stage and a second pumping stagc.
13. A pneumatic calibration device according to claim 12, wherein thc combined first and second pumping stages are arranged to produce a pressure in the chamber between 14 PSI and 5000 PSI.
14. A pneumatic calibration device according to any preceding claim, wherein the test device connector, the presstLre gauge connector or both extend from the pump body, and wherein none of the connectors extending from the pump body extend in a direction of the movement of the pump ever towards the pump body during operation of the pump.
A pneumatic calibration device according to claim 14, wherein at least one or both of the adjustment mechanism and pressure gauge connector extend from the pump body in a direction perpendicular to a plane in which the pump lever moves during operation of the pump.
16. A pneumatic calibration device according to any one or more of claims 1 to 13, comprising a remote control member in fluid communication with the pump via a tube, wherein any one or more of the adjustment mechanism, pressure gauge connector and test device connector are provided on the remote control member.

17, A pneumatic calibration device according to claim 16, wherein the fiexibe tube has a length between 5 ft (about 1,5 m) and 10 ft (about 3 m).I. A pneumatic calibration device according to any preceding claim wherein the adjustment mechanism comprises an adjustment member arranged to alter the volume of the chamber. thereby adjusting the pressure in the chamber, 19. A pneumatic calibration device according to any preceding claim wherein the pump is foot operated.20. A pneumatic calibration device substantially as described herein with reference to the any one or more of the accompanying drawings.