GB2215404A - Syringe - Google Patents

Abstract

A syringe (10) which is intended for extracting a liquid sample for testing purposes, and for dispensing a controlled volume of the sample, comprises a hollow syringe body (11) having a port (12) at one end and a cup-shaped base support (13) at its opposite end, on which the syringe body (11) can rest to be supported in an upright position for storage purposes. A double piston assembly (14) is reciprocable in the syringe body (11) to carry out an air expulsion stroke towards the port, and a liquid extraction stroke away from the port so as to draw a liquid sample into the body. A handle (15) can be coupled with the piston assembly in either one of two modes of engagement whereby in the first mode of engagement the inner and outer pistons (17) and (16) of the piston assembly (14) move jointly during the air expulsion stroke and the liquid extraction stroke, but in the second mode of engagement only the inner piston (17) carries out limited axial movement relative to the outer piston in order to dispense a predetermined volume of the extracted liquid sample. <IMAGE>

Description

SYRINGE This invention relates to a syringe for extracting a liquid sample, and for dispensing a controlled volume of the sample.

The invention has been developed primarily in connection with a syringe for extracting a sample of lubricating oil used in a machine, since a study of an oil sample enables conclusions to be reached with regard to the operating condition of the machine. Thus, regular samples of lubricating oil used in expensive machines (and especially machines whose failure could give rise to serious interruption of production or accidents) can enable advance warning to be given of a potentially hazardous condition developing, or a machine failure. As moving parts wear out, fine metal particles are formed which are carried as fine suspensions in the oil, and a study of the proportion and size of these particles can give an advance warning of a machine failure.Also, badly fitting parts, such as worn bearings, can cause excessive generation of heat and degradation of the oil, which may also be able to be detected by routine sampling and testing of the lubricating oil.

In industries, such as the coal extraction industry, very heavy duty equipment operates in arduous conditions, and it is important to keep a close watch on the operating performance, and to have advance warning of any potential hazard (fire) or machine failure developing. Therefore, it is the practice for oil syringes to be used, which extract a sample of oil from e.g. a gearbox, by way of a suction pipe, and for this sample to be stored in an incubator for a set period (often a period of days) and then for portions of the sample to be dispensed for various tests to be carried out.

The invention is therefore particularly concerned with an oil syringe for use in extracting samples of oil for subsequent testing, and having improved means for handling the sample and for operating the syringe.

According to the invention there is provided a syringe for extracting a liquid sample for testing purposes, and for dispensing a controlled volume of the sample, and which comprises: a hollow syringe body having a port at one end and a support at its opposite end on which the body can rest to be supported in an upright position; a piston assembly reciprocable in said hollow body and movable in an air expulsion stroke towards the port, and movable in a liquid extraction stroke away from the port so as to draw a liquid sample into the body; and, a handle for reciprocating said piston assembly in said body; in which: the handle is detachably coupled with said piston assembly whereby the handle can be detached when a liquid sample has been extracted and so that the body can be supported in an upright position on said support; and, the piston assembly includes an outer piston and an inner piston mounted in the outer piston, the handle and the piston assembly having a first mode of engagement whereby the inner and outer pistons are movable jointly by the handle during the air expulsion stroke and the liquid extraction stroke, and a second mode of engagement whereby the inner piston can carry out limited axial movement relative to the outer piston in order to dispense a predetermined volume of the extracted liquid sample.

Thus, by providing the detachable handle, the syringe can be readily stored in an upright position, resting on the support at said opposite end of the syringe body, following extraction of the liquid sample and uncoupling of the handle, and this is especially useful when prolonged storage of the sample may be required, prior to testing operations being carried out. In addition, by providing the two modes of engagement of the handle with the piston assembly, and particularly in the second mode of engagement, a carefully controlled and predetermined smaller volume of an extracted liquid sample can be dispensed in a simple and automatically controlled manner.

Also, the operation can be repeated, if further predetermined volume portions of the sample are required at a later date.

Preferably, said opposite end of the syringe body comprises a cup-shaped base, and coupling,means attached to said piston assembly is preferably housed within this cup shaped base, so as not to project therefrom. The handle then has a co-operative coupling portion which can make engagement with said coupling means in either the first or the second modes of engagement, according to requirements.

Conveniently, the coupling means is receivable by a socket at one end of the handle, and may be provided with laterally projecting pins which control the depth of engagement of the socket therewith, depending upon the manner by which the handle is presented to the coupling means.

Preferably, the syringe body is shaped to define a void at the end adjacent to said port, which is unswept by the piston assembly during its reciprocation, whereby an air void is formed so that air is trapped within the body during extraction of a liquid sample. For certain liquid testing purposes, it is advantageous for a small proportion of air to be present in order to promote thorough mixing of the sample prior to dispensing of a controlled volume of the sample for testing purposes.

The socket may therefore be provided with a first slot which receives said coupling pins in the first and second modes of engagement, and a second slot which receives the coupling pins when the handle is operated to discharge any air which may be present in the syringe body in the air void above an extracted liquid sample. The slots are of different depths, in order to control the depth of reception of the coupling means in the socket, whereby the socket end of the handle can engage drivingly with the inner piston when in the first and second modes of engagement, whereas it can only make driving engagement with the outer piston during an air purging stroke.

Three embodiments of syringe according to the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of an operating handle and syringe body of the syringe according to the invention, with the handle being shown in a first mode of engagement with a piston assembly of the syringe; Figure 2 is a detail view of the socket end of the handle in an alternative operating position suitable for a second mode of engagement with the piston assembly; Figure 3 is an exploded view of a modified embodiment; Figure 4 is an exploded view, in section, of a third embodiment of syringe according to the invention; Figure 5 is a side view of an operating handle for the syringe shown in Figure 4; and, Figure 6 is a side view of the operating handle of Figure 5 in an alternative operating position.

Referring now to Figure 1 of the drawings, a syringe according to the invention is designated generally by reference 10 and is intended for extracting a liquid sample for testing purposes, and for dispensing a controlled volume of the sample. The syringe 10 comprises a hollow syringe body 11 having a port 12 at one end and a cupshaped base support 13. at its opposite end, on which the syringe body 11 can rest to be supported in an upright position for storage purposes.

A piston assembly 14 is reciprocable in the syringe body 11 and is movable in an air expulsion stroke, from the position shown in Figure 1, towards the port 12, and is movable in an opposite direction away from the port 12 in a liquid extraction stroke so as to draw a liquid sample into the body. A handle 15 is detachably coupled with the piston assembly 14, whereby the handle 15 can be detached when a liquid sample has been extracted, and so that the body can be supported in an upright position on the cup shaped base support 13.

The piston assembly 14 includes an outer piston 16 and an inner piston 17 which is mounted in the outer piston.

Also, a coupling member 18 projects from the axially outer end of the inner piston 17 so as to be located within the base 13, for engagement by a socket end 19 of the handle 15 in either a first mode of engagement, or a second mode of engagement, as described in more detail below. The inner piston neck 29 has a further spiral running down it and a peg 30 in the outer piston 16 locates in the spiral.

In the first mode of engagement, (which is illustrated in Figure 1), the socket 19 can engage over the coupling member 18 so that coupling pins 20 of the member 18 are received in a first slot 24 of the socket 19, and a lower surface 27 of the socket 19 engages an upper surface 28 of outer piston 16. In this first mode of engagement, the pistons 16 and 17 of the piston assembly can be moved jointly by the handle 15 during the air expulsion stroke, and also during the liquid extraction stroke, though prior to commencement of the extraction stroke the handle 15 is rotated so as to latch the coupling pins 20 in a holding portion 21a of a second slot 21.

The port end 25 of the body 11 is dome-shaped so as to define an air void 26 which cannot be swept during movement of the piston assembly, and this enables a small volume of air to be retained in the syringe body with an extracted charge of liquid sample. This air pocket is useful in the testing of certain liquid samples, such as lubricating oils, as it promotes mixing of the sample prior to dispensing of a controlled volume for testing purposes.

Following completion of the liquid extraction stroke, the handle 15 can then be disengaged from the coupling member 18, and the syringe may then be placed in an incubator prior to subsequent testing of the liquid sample.

However, prior to dispensing of a controlled volume of the sample, the handle is rotated to the position shown in Figure 2, so that the coupling pins 20 can move within a deeper slot 24 in the socket 19, whereby subsequent depression of the handle 15 causes displacement of the inner and outer pistons 16 and 17, in order to discharge the air present by engagement between end 27 of the socket 19 and end surface 28 of the outer piston 16.

Following the discharge of the air present in the body 16, the handle i5 is adjusted so as to bring the pins 20 into engagement in the slots 21, and in this second mode of engagement the handle 15 is able to dispense a controlled volume of the sample in the syringe body 11 by depressing the handle 15 which moves the inner piston 17 in a spiral movement until it comes into engagement with end surface 28 of the outer piston 16.

A further dispensing of a controlled volume of sample may be carried out by withdrawing the inner piston 17 (by rotating the handle 15 so that pins 20 are held captive by recesses 21a of slots 21), and then carrying out a further depression of the handle 15 in a direction towards the port 12 (after having purged the syringe body again of any drawn-in air).

A modified embodiment is shown in Figure 3, in which a longer nozzle 12a is provided having a reference line 12b spaced a predetermined distance upwardly of its tip end.

There is also a spiral groove 31 formed in the stem 32 of coupling member 18a, which is engaged by a peg 33 projecting inwardly from the inner wall of piston assembly 14a. Downward movement of the coupling member 18a is therefore accompanied by rotation, and this improves the operation of the modified assembly, as also does the increased length of nozzle 12a.

Referring now to Figures 4 to 6, there is shown a third embodiment of syringe according to the invention, which is designated generally by reference 40, and which comprises a hollow syringe body 41 having a port 42 at one end and a cup shaped base support 43 at its opposite end, on which the syringe body 41 can rest to be supported in an upright position for storage purposes. A piston assembly 44 is reciprocable in the syringe body 41 and is movable in an air expulsion stroke, from the position shown in Figure 4, towards the port 42, and is movable in an opposite direction away from the port 42 in a liquid extraction stroke so as to draw a liquid sample into the body.A handle 45 is detachably coupled with the piston assembly 44, whereby the handle 45 can be detached when a liquid sample has been extracted, and so that the body can be supported in an upright position on the cup shaped base support 43.

The piston assembly 44 includes an outer piston 46 and an inner piston 47 which is mounted in the outer piston.

Also, a coupling member 48 projects from the axially outer end of the inner piston 47 so as to be located within the base 43, for engagement by a socket end 49 of the handle 45 in either a first mode of engagement, or a second mode of engagement, as described in more detail below.

Figure 5 shows the handle 45 in an operative position suitable for the first mode of engagement, whereas Figure 6 shows the handle 45 in a second operative position suitable for carrying out a second mode of engagement. In Figure 5, the socket 49 is shown having a short length receiving recess 50 which can engage with the coupling member 48 in the first mode of engagement, whereby the pistons 46 and 47 of the piston assembly can be moved jointly by the handle 45 during the air expulsion stroke, and also during the liquid extraction stroke. Following completion of the liquid extraction stroke, the handle 45 can then be disengaged from the coupling member 48, and the syringe may then be placed in an incubator prior to subsequent testing of the liquid sample.However, prior to dispensing of a controlled volume of the sample, the handle 45 is rotated to the position shown in Figure 56, so that a recess 51 formed in the socket 49 and having a deeper entrance than recess 50, can permit the socket 49 to slide over the coupling member 48 until the free end 52 of the socket can come into abutment with the outer piston 46 to permit necessary small axial movement of the outer piston to achieve discharge of any air present in the housing 41 adjacent to the port 42 following standing of the sample in the incubator.

In the first mode of engagement of the handle 45 when recess 50 engages the coupling member 48, a controlled sample of the liquid can be dispensed e.g. two millilitres, and this may be achieved by turning the handle 45 through a predetermined angle e.g. 900. An external spiral (not shown) may be provided on the stem of the inner piston 47, which engages with a flange 53 of the outer piston 46, so that the inner piston 47 moves axially within the outer piston 46 to cause dispensing of the controlled small sample of liquid.

Claims (8)

1. A syringe for extracting a liquid sample for testing purposes, and for dispensing a controlled volume of the sample, and which comprises: a hollow syringe body having a port at one end and a support at its opposite end on which the body can rest to be supported in an upright position; a piston assembly reciprocable in said hollow body and movable in an air expulsion stroke towards the port, and movable in a liquid extraction stroke away from the port so as to draw a liquid sample into the body; and, a handle for reciprocating said piston assembly in said body; in which: the handle is detachably coupled with said piston assembly whereby the handle can be detached when a liquid sample has been extracted and so that the body can be supported in an upright position on said support; and, the piston assembly includes an outer piston and an inner piston mounted in the outer piston, the handle and the piston assembly having a first mode of engagement whereby the inner and outer pistons are movable jointly by the handle during the air expulsion stroke and the liquid extraction stroke, and a second mode of engagement whereby the inner piston can carry out limited axial movement relative to the outer piston in order to dispense a predetermined volume of the extracted liquid sample.

2. A syringe according to Claim 1, in which said opposi.te end of the syringe body comprises a cup-shaped base, and coupling means attached to said piston assembly is housed within said cup-shaped base so as not to project therefrom.

3. A syringe according to Claim 2, in which the coupling means is receivable by a socket at one end of the handle.

4. A syringe according to Claim 3, in which the coupling means is provided with laterally projecting pins which control the depths of engagement of the sockets therewith.

5. A syringe according to any one of the preceding claims, in which the syringe body is shaped to define a void at the end adjacent to said port, which is unswept by the piston assembly during its reciprocation, whereby an air void is formed so that air is trapped within the body during extraction of a liquid sample.

6. A syring according to Claim 4 or 5, in which the socket is provided with a first slot which receives said coupling pins in the first and second modes of engagement, and a second slot which receives the coupling pins when the handle is operated to discharge any air which may be present in the syringe body in the air void above an extracted liquid sample.

7. A syringe according to Claim 1, in which the handle is provided with a socket having two recesses, one of which extends inwardly of the socket to a greater extent than the other recess, so that said one recess enables the socket to function in said second mode of engagement with the coupling member, and the other recess enables the socket to function in said first mode of engagement with the coupling member.

8. A syringe according to Claim 1 and substantially as hereinbefore described with reference to, and as shown in any of the embodiments illustrated in the accompanying drawings.