DE19718454B4 - differential pressure gauge - Google Patents

Abstract

Differential pressure gauge (10) with a sensor unit (34) for determining the differential pressure between a first conduit (28, 36) having a first fluid port (20) and the sensor unit (34) interconnects, and a second Line (30, 38) having a second fluid port (22) and the Sensor unit (34) connects to each other, a zero-point setting device (40) for adjusting the zero point of the differential pressure measuring device (10), one the first line (28, 36) and the second line (30, 38) connecting bypass (12), a valve (33) on one side to open the bypass (12) and for closing the lines (28, 36; 30, 38) and on the other side to close the bypass (12) and to open the Lines (28, 36, 30, 38) is formed, and an output unit (44), which measures the differential pressure measured by the sensor unit (34) via a communication link (50) with a remote monitoring / measuring station sends to this, characterized in that a position sensor (42) consisting of a stationary Detection unit (56) and one with ...

Description

The The invention relates to a differential pressure measuring device according to the preamble of claim 1 specified type.

such Differential pressure gauges become Flow of lines or for level measurement of containers used and are, for example, by the company Foxboro by their Series 863 DP known.

This Differential pressure gauge has while next to a measuring unit a connection unit on, the one by means of a valve switchable bypass between one connected to a high pressure port and one connected to a low pressure port Line has. The bypass usually becomes the zero point setting of the differential pressure measuring device activity of the valve switched on or opened and at the same time closed the line to the high pressure and low connection. For the Operating case is over the valve closes the bypass line and the line to the high pressure and low pressure connection open to not to affect the function of the differential pressure gauge. Therefor it is necessary to determine the position of the valve and thus the opening and closed position of the bypass.

A Such control was previously carried out by a visual inspection on the spot on Differentialdruckmeßgerät, the but expensive and expensive.

Out WO 95/24625 a connection unit is known in which two Shut-off devices and two channels are designed to prevent misuse. The Security refers to a possible one-sided overload of the differential pressure transmitter. In contrast to the generic Differenzdruckmeßgerät is however no bypass that can be closed for zero point adjustment by means of a shut-off valve intended.

Farther especially in level measurement currently many mechanical Differenzdruckmeßgeräte with a display directly on Instrument suburb used. Such a differential pressure gauge, for example, reveal the datasheets PM 07.05 and 09.11 from the company WIKA. The pressure gauge disclosed there (type 732.51) has a mechanical measuring mechanism and an on-site display by means of a pointer and dial. As options are a zero point corrector and a pressure balance valve intended.

The associated pressure compensation valve (AM 09.11, page 3) can be used as a single or triple valve executed be. The operation the valves take place by turning the toggle handle of the respective spindle valve. For a Triple valve means that, taking into account the order three times a spindle must be turned.

to Simplification of valve actuation are also known Einhebelventile, such as the copies of the data sheets "changeover valve" of the valve factory F. Schneider or "low pressure double three-valve" from Hartmann & Braun AG show. By turning a single tap, both a bypass and also two shut-off valves are opened or closed to the medium.

Of the Desire for cost savings and better monitoring both the measuring devices as too over waking media led reinforced on the development of new devices, the opportunity the remote query of the determined by the differential pressure gauge Differential pressure, for example, from a remote from the monitored tank Remote monitoring station allow. This is due to the aforementioned generic differential pressure gauge of the Fa. Foxboro allows.

Out The US-PS 3,596,680 is a differential pressure gauge with a Differential pressure transmitter and a valve block with two valves and revealed a bypass. The differential pressure is connected via a signal line to control unit forwarded. The valve block has two separately operable Valves open, which turn the bypass on and off.

In It is used in many applications of differential pressure gauges for security reasons - such as in hospitals - or out business reasons necessary in the tank monitored by the differential pressure gauge re-order the tank medium in time, at any time to ensure a secure supply with the tank medium. In these cases is the remote query of the level of the monitored tank or at least the limit value corresponding to a minimum value the level necessary for the tank.

Of the Invention is based on the object, a differential pressure measuring device according to the im Preamble of claim 1 specified type to develop such that easy monitoring the opening or closed position of the bypass allows becomes.

These Task is achieved by the characterizing features of claim 1 solved in conjunction with its generic features.

The under claims represent advantageous embodiments of the invention.

Of the Invention is based on the finding that by providing a position sensor of the valve detecting position sensor and a connected to the position sensor output unit of the sensor unit of the differential pressure gauge a remote monitoring the opening or closed position of the bypass is made possible in a simple manner. A review before Location can be omitted. about the output unit thus becomes both the measured value of the sensor unit as well as the position of the valve issued / forwarded.

To The invention is therefore a position sensor consisting of a stationary detection unit and one provided with the valve triggering element, which the Position of the valve and thus the opening and closing state of the bypass and the lines detected, the position sensor with the output unit is connected, so that a remote query of the position of the valve is enabled. In addition, one comprising the sensor unit and the detection unit Measuring unit and a valve comprising the trigger element and the bypass Connection unit provided, which together form the differential pressure gauge. The measuring unit and the connection unit are detachable with each other connected. This modular design makes the interchangeability for maintenance or repair tasks.

Thereby in that the measuring unit and the connection unit are detachably connected to one another are achieved, that also on site replacement or repair work easy and fast running can be.

Around the adjustability of the valve does not affect the position sensor works according to a embodiment the invention contactless.

Especially is the trigger element provided with a permanent magnet and sends the detection unit dependent on the magnetic field of the permanent magnet signals to the output unit. Therefor the detection unit has a REED switch.

According to one another embodiment is the detection unit over a microprocessor connected to the output unit. this has the advantage that the various signals of the detection unit, the sensor unit and the zero point adjustment in a fold Way according to one definable relationship to a state characterizing the state of the differential pressure gauge Signal linked can be.

The Output unit or the microprocessor receives from the detection unit preferably a binary signal representing the valve position. Advantageously, the signal can thus be further processed directly by the processor or also be transmitted from the output unit directly to a remote monitoring station.

According to one embodiment The invention is the valve over actuated a valve handle, in particular, the valve handle in the position for normal operation can be mechanically secured. An unintentional adjustment the valve handle and the valve coupled thereto is characterized prevented.

moreover the valve handle can be sealed / sealed in the position for normal operation become.

Around To ensure a high efficiency of the position sensor, the trigger element is designed sector-shaped and rotatably supported about an axis.

The casing the measuring unit also has a recess adapted to the triggering element on. Permanent magnet and detection unit can thereby in only a small Distance to be arranged.

Further Advantages and features of the invention will become apparent from the description an embodiment in connection with the drawing. Show it:

1 a schematic view of a Differenzdruckmeßgerätes according to an embodiment of the invention with open bypass; and

2 a schematic representation of the Differenzdruckmeßgerätes as in 1 , but with closed bypass.

1 shows a schematic representation of a differential pressure gauge 10 according to the invention with an open and 2 with a closed bypass line 12 , The differential pressure gauge 10 consists of a measuring unit 14 and one with this about screws 16 detachably connected connection unit 18 ,

The connection unit 18 has a high pressure connection 20 , a low pressure connection 22 , one to the high pressure connection 20 associated port 24 for the measuring unit 14 and another, the low pressure port 22 associated port 26 for the measuring unit 14 on. The connections are for example at the top and bottom egg Tanks connected to monitor the supply of the medium within the tank.

A first line 28 connects the connection 24 to the measuring unit 14 with the high pressure connection 20 , a second line 30 connects the connection 26 to the measuring unit 14 with the low pressure connection 22 and the bypass line 12 connects the connection 24 and the connection 26 together. The administration 12 Branches each of the lines 28 and 30 and forms a bypass between connection 20 and connection 22 ,

One by means of a valve handle 32 switchable valve 33 works with the wires 28 . 30 and the bypass line 12 so together, that if the bypass 12 open, the line 28 to the high pressure connection 20 and the line 30 to the low pressure connection 22 are interrupted - 1 -, and if the bypass 12 closed, the line 28 to the high pressure connection 20 and the line 30 to the low pressure connection 22 are open - 2 -.

The first-mentioned valve position forms the bypass operation and the second said valve position normal operation of the differential pressure gauge 10 ,

An additional in the connection unit 18 provided test connection 31 offers the possibility to display the resulting static fluid pressure with or without transmitter. The static fluid pressure is often determined additionally for safety monitoring. Furthermore, the static fluid pressure for plausibility check of the measured differential pressure or for the correction of the static pressure influence of the sensor unit 34 serve. A necessary link between the static pressure and the differential pressure can be found both in the control system and in the processor 46 the measuring unit 14 respectively.

The measuring unit 14 is with a sensor unit 34 for determination of itself via the high-pressure connection 20 and the low pressure port 22 adjusting differential pressure and with the connections 24 and 26 the connection unit 18 provided connections assigned. For clarity, the mating connectors are 24 and 26 the measuring unit 14 and the connection unit 18 provided with the same reference number.

A line 36 connects the connection 24 - High pressure - with the sensor unit 34 and a line 38 the connection 26 - Low pressure - with the sensor unit 34 ,

The measuring unit 14 further includes a manually operable zero-point adjuster 40 for adjusting the zero point of the sensor unit 34 , a position sensor 42 for determining the position of the valve 33 and thus the opening state of the bypass 12 as well as the lines 28 and 30 , an output unit 44 as well as a microprocessor 46 on.

The microprocessor 44 is with the zero point adjuster 40 , the position sensor 42 , the sensor unit 34 and the output unit 44 each via signal lines 48 connected. The output unit 44 is again with a remote monitoring station via connecting lines 50 connected via the remote transmission of the measured differential pressure by means of electrical standard signals. The two connecting lines 50 be common as both so-called two-wire devices for both the transmission of the electrical signal with respect to the differential pressure and the power supply of the differential pressure 10 used.

In the case 52 the measuring unit 14 there is a sector-shaped recess 53 in the shape of one with the valve handle 32 coupled triggering element 54 is adapted.

The trigger element 54 is part of the two-part position sensor 42 , wherein the further part by a in the measuring unit 14 firmly arranged detection unit 56 is formed. In the trigger element 54 is a permanent magnet 58 inserted so that this bypass operation and thus in the one valve position relative to the detection unit 56 away - 1 - And in normal operation and thus in the other valve position relatively close to the detection unit 56 is arranged - 2 -.

Through the recess 53 in the case 52 the assembly is simplified and there is a small distance between the trigger element 54 and the detection unit 56 guaranteed.

With actuation of the valve handle 32 , the coupled valve 33 and in turn coupled triggering element 54 becomes an axis 60 made a rotation about 90 °. The permanent magnet 58 in the trigger element 54 changes its position relative to that in the measuring unit 14 fixed detection unit 56 , The distance becomes larger or smaller depending on the rotation and the starting position.

In the detection unit 56 is a reed switch 62 integrated. At an approximation of the permanent magnet 58 closes the reed switch 62 , The bypass is closed (normal operation) - 2 -. Removes the permanent magnet 58 from the reed switch 62 , the bypass will be 12 opened and the wires 28 and 30 to the High-pressure connection 20 and low pressure connection 22 closed (bypass operation) - 1 -. The microprocessor 56 recognizes as a result of the connection to the detection unit 56 that the bypass 12 is opened and transmits this information via the output unit 44 and the connection lines 50 in a remote monitoring / measuring station.

There are two different modes of transmission:
Following commissioning or following a zero-point adjustment, a serial transfer of some initialization data, such as data, will occur. B. device number, medium and valve position, while in normal operation, a known analog two-wire signal between 4 mA to 20 mA is transmitted, which indicates the closed valve position.

To at z. B. undesired opening of the bypass during normal operation to indicate a warning signal, an analog error signal with an output current less than 3.6 mA or greater 22.8 mA output. The indication of such error is provided by the microprocessor 46 controlled.

Switching the valve 33 by means of the valve handle 32 in the position for normal operation happens by the valve handle 32 is rotated in the direction of arrow A by about 90 °, causing the valve handle 32 and the trigger element 54 the valve 33 around the axis 60 rotate.

2 shows that 1 corresponding differential pressure gauge 10 in normal operation, ie with closed bypass 12 and a line connection between the sensor unit 34 over the wires 28 and 36 to the high pressure connection 20 and another line connection between the sensor unit 34 over the line 30 and 38 to the low pressure connection 22 ,

The permanent magnet 58 with the valve handle 32 coupled triggering element 54 causes the in the detection unit 56 arranged reed switch 62 closed is. This information is sent via the signal line 48 from the detection unit 36 to the microprocessor 46 passed on and in the case of commissioning to confirm the correct valve position by means of the output unit 44 and the connecting lines 50 directed to the monitoring station.

Checking the zero point of the differential pressure - such as after refilling the tank - is done by turning the valve handle 32 initiated in the direction of arrow B.

An alternative embodiment of the invention includes a detection unit 56 with two reed switches 62 one of which closes in normal operation and the other in bypass mode. The positions of the valve handle 32 and thus the valve 33 , which correspond to neither of the two positions, can thus be considered as forbidden intermediate positions of the REED switches 62 detected and output as appropriate warning signals.

In another embodiment is used as a trigger element 54 a cam used in normal operation in the detection unit 56 arranged microswitch triggers.

Likewise, it is provided in another embodiment to use two such micro-switches, one of which in normal operation and the other in the bypass mode of one with the valve handle 32 connected cam can be triggered.

According to a further embodiment, the position sensor 42 implemented as a displacement sensor with continuous output. In this case, an inductive principle is particularly advantageous, wherein the triggering element 54 in a simple way from the permanent magnet 58 and the detection unit 56 consists of a soft magnetic core with coils on both ends. Such a displacement sensor is for example in the patent application P 197 01 520.4 ("Magnetic transducer") described, to which reference is made in full.

In another embodiment of the invention is provided, the valve handle 32 mechanically secure and seal in the position for normal operation, for example, with a screw to lock and protect in this position by a wire seal against changes.

The invention is characterized in that now a complete remote monitoring of a Differenzdruckmeßgerätes 10 is made possible by a position sensor 42 is used with binary or continuous output signals, the valve handle 32 and the valve coupled with it 33 to open and close the bypass 12 to monitor. This type of control is particularly easy and effective.

One Advantage of the invention is also the simplicity of the structure and the simple communication with the monitoring / measuring station. The transfer of detected by the microprocessor data can also be via a purely digital fieldbus, a frequency superimposed on the analogue signal, such as HART field communication protocol or other analog coding the error messages occur.

10

differential pressure gauge

12

Bypass line

14

measuring unit

16

screw

18

access unit

20

High-pressure connection

22

Low pressure connection

24

Connection to the measuring unit (High pressure)

26

Connection to the measuring unit (Low pressure)

28

Line connection 24 - High pressure connection 20

30

Line connection 26 - Low pressure connection 22

31

test connection

32

Valve handle

33

Valve

34

sensor unit

36

Line connection 24 - Sensor unit 34

(High pressure)

38

Line connection 26 - Sensor unit 34

(Low pressure)

40

Zero point setting

42

position sensor

44

output unit

46

microprocessor

48

signal lines

50

interconnectors

52

Housing of measuring unit

53

recess

54

triggering element

56

detection unit

58

permanent magnet

60

axis

62

REED switch

Claims (10)

Differential pressure gauge ( 10 ) with a sensor unit ( 34 ) for determining the differential pressure between a first line ( 28 . 36 ), which has a first fluid connection ( 20 ) and the sensor unit ( 34 ) and a second line ( 30 . 38 ), which has a second fluid connection ( 22 ) and the sensor unit ( 34 ), a zero-point adjuster ( 40 ) for adjusting the zero point of the differential pressure measuring device ( 10 ), the first line ( 28 . 36 ) and the second line ( 30 . 38 ) connecting bypass ( 12 ), a valve ( 33 ), on one side to open the bypass ( 12 ) and to close the lines ( 28 . 36 ; 30 . 38 ) and on the other side to close the bypass ( 12 ) and to open the lines ( 28 . 36 ; 30 . 38 ), and an output unit ( 44 ), which by means of the sensor unit ( 34 ) measured differential pressure via a communication link ( 50 ) with a remote monitoring / measuring station to this, characterized in that a position sensor ( 42 ) consisting of a stationary detection unit ( 56 ) and one with the valve ( 33 ) coupled trigger element ( 54 ) is provided, the position of the valve ( 33 ) and thus the opening and closing state of the bypass ( 12 ) as well as the lines ( 28 . 36 ; 30 . 38 ), wherein the position sensor ( 42 ) with the output unit ( 44 ), so that a remote query of the position of the valve ( 32 ) and that the sensor unit ( 34 ) and the detection unit ( 56 ) comprehensive measuring unit ( 14 ) as well as the valve ( 33 ) with the trigger element ( 54 ) and the bypass ( 12 ) comprehensive connection unit ( 18 ) form the differential pressure measuring device, wherein the measuring unit ( 14 ) and the connection unit ( 18 ) are releasably connected together. Differential pressure measuring device according to claim 1, characterized in that the position sensor ( 42 ) works without contact. Differential pressure measuring device according to claim 2, characterized in that the triggering element ( 54 ) with a permanent magnet ( 58 ) and the detection unit ( 56 ) as a function of the magnetic field of the permanent magnet ( 58 ) Signals to the output unit ( 44 ) sends. Differential pressure measuring device according to claim 3, characterized in that the detection unit ( 56 ) with at least one REED switch ( 62 ) is provided. Differential pressure measuring device according to one of claims 2 to 4, characterized in that the detection unit ( 56 ) via a microprocessor ( 46 ) with the output unit ( 44 ) connected is. Differential pressure measuring device according to claim 5, characterized in that the output unit ( 44 ) or the microprocessor ( 46 ) from the detection unit ( 56 ) receives a valve position representative binary signal. Differential pressure gauge according to one of the preceding claims, characterized in that the valve ( 33 ) via a valve handle ( 32 ) is pressed. Differential pressure measuring device according to claim 7, characterized in that the valve handle ( 32 ) is mechanically secured in the position for normal operation. Differential pressure measuring device according to claim 8, characterized in that the valve handle ( 32 ) is sealed / sealed in position for normal operation. Differential pressure measuring device according to one of the preceding claims, characterized in that the triggering element ( 54 ) sector shaped ausgebil det and rotatable about an axis ( 60 ) and the housing ( 52 ) of the measuring unit ( 14 ) one to the trigger element ( 54 ) adapted recess ( 53 ) having.