CN221256884U - Steam turbine emergency blocking device - Google Patents

Abstract

The utility model provides a steam turbine emergency blocking device, which belongs to the field of steam turbine control and comprises: the system comprises an AST safety oil circuit, a pressure oil circuit, four AST electromagnetic valves, four unloading valves and an emergency stop test pipeline, wherein each two electromagnetic valves are arranged in parallel, oil inlets of the electromagnetic valves are respectively connected with the pressure oil circuit, a working port of each electromagnetic valve is respectively connected with one unloading valve in series, and each unloading valve is respectively connected with the AST safety oil circuit and the emergency stop test pipeline; wherein, the two parallel electromagnetic valves are communicated with the two unloading valves through the pressureless oil return pipeline. The unloading valve can be controlled to act by controlling at least one of the two groups of electromagnetic valves connected in parallel to lose electricity, so that the AST safety oil way is controlled to drain oil through the AST oil drain channel, and further the closing of the main valve and the regulating valve is controlled. The utility model can prevent the misoperation of the unit from stopping due to the misoperation of a certain electromagnetic valve, or prevent the blockage and refusal of the certain electromagnetic valve from stopping safely when the unit is required to stop, thereby avoiding unnecessary loss.

Description

Steam turbine emergency blocking device

Technical Field

The utility model relates to the technical field of steam turbine control, in particular to a steam turbine emergency blocking device.

Background

The actuating mechanism of the turbine shutoff system is an indispensable component part in a turbine hydraulic system, and can stop the unit in a turbine critical state. In the prior art, the low-pressure turbine oil control scheme generally adopts a two-way mode, if any one of the actuating mechanisms malfunctions, the unit is stopped immediately.

In the prior art, a low-pressure turbine oil emergency interruption executing mechanism, namely a magnetic break throttle, is adopted, when a unit normally operates, a digital electrohydraulic control system enables the left side of a double-coil electromagnetic valve to be electrified, the unit seals an unloading valve under the action of pressure oil and spring force, and safety oil is established to enable the unit to hang a brake; in critical state, the emergency shutdown system charges the right coil, the oil pressure of the pipeline between the double-coil electromagnetic valve and the unloading valve is unloaded, the unloading valve is opened, and the unit is shut down due to the falling of safe oil pressure.

In the normal running process of the unit, if an engineer misoperates ETS, the double-coil electromagnetic valve is enabled to act, the unit is immediately stopped, the two-in-one type of stop protection mode is adopted, namely any action is adopted, the unit can be stopped, and the possibility of misoperation is high.

In view of the foregoing, the present utility model provides a steam turbine emergency shutdown device to reduce the possibility of false touch.

Disclosure of utility model

The utility model aims to provide a steam turbine emergency blocking device which can avoid the machine unit stop caused by the fault or misoperation of a certain electromagnetic valve.

The utility model provides a steam turbine emergency shutoff device, comprising: the system comprises an AST safety oil circuit, a pressure oil circuit, four AST electromagnetic valves, four unloading valves and an emergency stop test pipeline, wherein an AST1 electromagnetic valve and an AST3 electromagnetic valve are arranged in parallel, oil inlets of the AST1 electromagnetic valve and the AST3 electromagnetic valve are respectively connected with the pressure oil circuit, a working port of the AST1 electromagnetic valve is connected with a first unloading valve in series, a working port of the AST3 electromagnetic valve and a third unloading valve are connected with each other in series, and two ports of the first unloading valve and the third unloading valve are respectively connected with the AST safety oil circuit and the emergency stop test pipeline;

An AST2 electromagnetic valve and an AST4 electromagnetic valve are arranged in parallel, oil inlets of the AST2 electromagnetic valve and the AST4 electromagnetic valve are respectively connected with the pressure oil path, a working port of the AST2 electromagnetic valve and a second unloading valve are connected in series, a working port of the AST4 electromagnetic valve and a fourth unloading valve are connected in series, two ports of the second unloading valve and the fourth unloading valve are respectively connected with the pressure oil path and the emergency stop test pipeline, and the AST1 electromagnetic valve and the AST3 electromagnetic valve which are connected in parallel are connected with the second unloading valve and the fourth unloading valve through non-pressure oil return pipelines;

When the four AST electromagnetic valves are electrified, pressure oil enters the unloading valve connected with the pressure oil passage through each AST electromagnetic valve from the pressure oil passage, so that the unloading valve is closed, the AST safety oil passage is prevented from unloading, AST oil pressure is built, the unit is in a hanging state, and a main valve and an adjusting valve can be opened;

When at least one of the AST1 electromagnetic valve and the AST3 electromagnetic valve and at least one of the AST2 electromagnetic valve and the AST4 electromagnetic valve are controlled by a steam turbine stopping signal to be in power-off and closed, the unloading valve connected with the unloading valve acts, the AST safety oil way discharges oil through an AST oil discharge channel, the unit is in a switching-on state, and the main valve and the regulating valve are closed.

Preferably, the emergency stop test line is provided with two sets of ASP pressure switches for monitoring ASP oil pressure.

Preferably, one side of the ASP pressure switch is connected in parallel with an ASP pressure gauge.

Preferably, each ASP pressure switch and each ASP pressure gauge are connected to at least one shut-off valve.

Preferably, four groups of AST pressure switches and one group of AST pressure gauges are connected to the AST oil drain channel and used for monitoring the AST oil pressure.

Preferably, each AST pressure switch and the pipeline where the AST pressure gauge is located are connected with at least one stop valve, and the pipeline where the AST pressure gauge is located is also connected with a hydraulic control one-way valve.

Preferably, an inlet orifice is arranged between the first unloading valve, the third unloading valve and the emergency stop test pipeline, and an outlet orifice is arranged between the emergency stop test pipeline and the pressureless oil return pipeline.

Preferably, the valve further comprises a valve block, wherein the AST1 electromagnetic valve and the AST3 electromagnetic valve are installed on the same side of the top end of the valve block, and the AST2 electromagnetic valve and the AST4 electromagnetic valve are installed on the same side of the bottom end of the valve block.

Preferably, the AST safety oil path, the pressure oil path, the emergency stop test pipeline and the pressureless oil return pipeline are all arranged in the valve block, each unloading valve is arranged in the valve block, and the opening and closing sizes of the inlet orifice and the outlet orifice are adjusted by the system pressure.

Preferably, the front face of the valve block is provided with an AST (automatic service) connecting hole and an ASP connecting hole, and the side face of the valve block is provided with an pressureless oil return hole communicated with a pressureless oil return pipeline.

Compared with the prior art, the utility model has the following beneficial effects:

four AST electromagnetic valves (emergency stop electromagnetic valves) are adopted, the four electromagnetic valves are automatically controlled by a turbine stop signal, in normal operation, all AST electromagnetic valves are electrified to be opened, pressure oil enters a spring chamber of an unloading valve through the AST electromagnetic valves to close the unloading valve, an AST safety oil path is prevented from unloading through an AST oil release channel, AST oil pressure is established, a unit is in a hanging gate, and a main valve and an adjusting valve of the turbine can be opened; the four AST electromagnetic valves are arranged in series after being connected in parallel, when at least one AST electromagnetic valve out of two groups of AST1 electromagnetic valve, AST3 electromagnetic valve, AST2 electromagnetic valve and AST4 electromagnetic valve is closed, the AST safety oil path is unloaded through an AST oil drainage channel, the AST safety oil path is in emergency and is out of pressure, so that a main valve and an adjusting valve are closed to stop a unit, the unit can be prevented from being stopped when a certain electromagnetic valve is in misoperation under certain condition, the unit is stopped when the misoperation is caused, or the unit is required to be stopped under emergency, and the unit can be safely stopped when the situation such as jamming exists in the certain electromagnetic valve is prevented;

2. By arranging the emergency stop test pipeline, the test operation can be carried out in a remote place, the safety risk is increased due to the fact that an engineer performs the on-site operation is avoided, a pressure switch can be arranged on the emergency stop test pipeline (ASP for short) and used for monitoring the pressure of the ASP, the on-line test function of an AST electromagnetic valve is met, and the problem that in the regular test process of the conventional emergency blocking device, only the engineer can perform the manual isolation operation on site, and the manual recovery is performed after the test is finished, so that a large potential safety hazard exists is solved;

3. the control logic is reliable, highly integrated, without excessive human intervention, and can be tested in one-touch.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present utility model, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a device according to an embodiment of the present utility model;

FIG. 2 is a front view of a second embodiment of the present utility model;

FIG. 3 is a top view of a second embodiment of the present utility model;

FIG. 4 is a left side view of a second embodiment of the present utility model;

FIG. 5 is a cross-sectional view of a second embodiment of the present utility model taken along line B-B in FIG. 2;

FIG. 6 is a cross-sectional view of a second embodiment of the present utility model taken along line C-C of FIG. 4;

FIG. 7 is a cross-sectional view of a second embodiment of the present utility model taken along line E-E of FIG. 2;

Reference numerals illustrate:

1: AST1 solenoid valve; 2: an AST2 solenoid valve; 3: AST3 solenoid valve; 4: AST4 solenoid valve; 5: a first unloading valve; 6: a second unloading valve; 7: a third unloading valve; 8: a fourth unloading valve; 9: a pressureless oil return pipeline; 10: an AST oil drainage channel; 11: an AST pressure switch; 12: an AST pressure gauge; 13: a stop valve; 14: a hydraulically controlled one-way valve; 15: an ASP pressure switch; 16: ASP manometer; 17: an inlet orifice; 18: an outlet orifice; 19: a valve block; 20: a damping element; 21: a process plug; 22: pressing and plugging; 23: and (5) a screw plug.

Detailed Description

The technical solutions of the present utility model will be clearly and completely described in connection with the embodiments, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present utility model, the meaning of "a plurality" is two or more, unless explicitly defined otherwise. Furthermore, the terms "mounted," "connected," "coupled," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

Example 1

As shown in fig. 1, the present utility model provides a steam turbine emergency shutdown device, comprising: an AST safety oil path (shown as AST in fig. 1), a pressure oil path (shown as HP 1-HP 2 in fig. 1), four AST electromagnetic valves, four unloading valves and an emergency stop test pipeline (shown as ASP in fig. 1), wherein an AST1 electromagnetic valve 1 and an AST3 electromagnetic valve 3 are arranged in parallel, oil inlets of the two electromagnetic valves are respectively connected with the pressure oil path, a working port of the AST1 electromagnetic valve 1 is connected with a first unloading valve 5 in series, a working port of the AST3 electromagnetic valve 3 is connected with a third unloading valve 7 in series, and two ports of the first unloading valve 5 and the third unloading valve 7 are respectively connected with the AST safety oil path and the emergency stop test pipeline; the working port of the AST2 electromagnetic valve 2 is connected with the second unloading valve 6 in series, the working port of the AST4 electromagnetic valve 4 is connected with the fourth unloading valve 8 in series, two ports of the second unloading valve 6 and the fourth unloading valve 8 are respectively connected with the pressure oil circuit and an emergency stop test pipeline, and the parallel-connected AST1 electromagnetic valve 1 and AST3 electromagnetic valve 3 are connected with the second unloading valve 6 and the fourth unloading valve 8 through a non-pressure oil return pipeline 9.

The precondition for realizing the start-up and normal operation of the steam turbine is that the safe oil pressure (AST oil pressure is about 1.96 MPa) is established, and once the AST oil pressure is lost, the main valve and the regulating valve are immediately closed, and the steam turbine generator unit is stopped. The device realizes the establishment of safety oil by using 4 AST electromagnetic valves and 4 unloading valves, when all AST1 electromagnetic valves 1, AST2 electromagnetic valves 2, AST3 electromagnetic valves 3 and AST4 electromagnetic valves 4 are electrified, pressure oil (HP 1 or HP2, the pressure is about 1.98 MPa) enters spring chambers of corresponding unloading valves connected with the pressure oil channels through the AST electromagnetic valves by pressure oil channels, so that the unloading valves are closed, the AST safety oil channels are prevented from unloading, AST oil pressure is established, the unit is in a hanging state, and a main valve and an adjusting valve can be opened.

When at least one of the AST1 solenoid valve 1 and the AST3 solenoid valve 3 and at least one of the AST2 solenoid valve 2 and the AST4 solenoid valve 4 (i.e., comprising the simultaneous operation of the AST1 solenoid valve 1 and the AST2 solenoid valve 2, the simultaneous operation of the AST1 solenoid valve 1 and the AST4 solenoid valve 4, the simultaneous operation of the AST3 solenoid valve 3 and the AST2 solenoid valve 2, the simultaneous operation of the AST3 solenoid valve 3 and the AST4 solenoid valve 4, the simultaneous operation of the AST1 solenoid valve 1, the AST2 solenoid valve 2 and the AST3 solenoid valve 3 and the AST4 solenoid valve 4) are controlled by a steam turbine stop signal to be in a power-off state, the corresponding unloading operation of the AST1 solenoid valve 3 and the AST4 solenoid valve is controlled by a steam turbine stop signal, the AST1 drain passage 10 is connected to the AST safety oil, and the main unit is in a throttle valve and a throttle valve is closed state.

By the control logic of the AST electromagnetic valve, the unit can be prevented from being stopped by misoperation when a certain electromagnetic valve (such as an AST1 electromagnetic valve 1) is in a certain condition, or the unit can be prevented from being stopped by misoperation or incapacitated when the unit is required to be stopped when the condition such as jamming exists in a certain electromagnetic valve (such as an AST1 electromagnetic valve 1) in an emergency condition, and the unit can be prevented from being stopped safely by matching at least one of the AST3 electromagnetic valve 3, the AST2 electromagnetic valve 2 and the AST4 electromagnetic valve 4 in the same group, so that the situation that the unit is stopped by misoperation or the unit cannot be stopped safely caused by single electromagnetic valve faults or mistaken touch is avoided, and unnecessary loss is avoided.

Four sets of AST pressure switches 11 and one set of AST pressure gauges 12 are connected to the AST drain passage 10, and since the AST pressure switches 11 and the AST pressure gauges 12 are both communicated with the AST safety oil passage, the AST drain passage can be conveniently used for monitoring the AST oil pressure, whether the safe AST oil pressure is established during normal operation of the unit can be judged, and the AST safety oil can be judged by the oil pressure after the AST drain passage 10 drains, and if the measured oil pressure is abnormal, a corresponding signal can be sent through the AST pressure switch 11. At least one stop valve 13 is connected to the pipeline where each AST pressure switch 11 and AST pressure gauge 12 are located, in this embodiment, the number of stop valves 13 on each branch is two, and a hydraulic control one-way valve 14 is also connected to the pipeline where the AST pressure gauge 12 is located, so that the flow direction of pressure oil can be controlled through the hydraulic control one-way valve.

In this embodiment, two sets of ASP pressure switches 15 are installed on an emergency stop test pipeline (abbreviated as ASP) for monitoring the oil pressure of the ASP, an ASP pressure gauge 16 is connected in parallel to one side of the ASP pressure switch 15, and at least one stop valve 13 is connected to each of the ASP pressure switches 15 and the pipeline where each ASP pressure gauge 16 is located. The scheme can also carry out test operation in a remote place, avoids the on-site operation of engineering operators, increases the safety risk and meets the on-line test function of the AST electromagnetic valve. When the system is normally operated, the ASP oil pressure is about 0.98Mpa, and when in on-line test, the ASP oil pressure must be normal, and only a single AST electromagnetic valve can be powered off, and the ASP oil pressure cannot be simultaneously carried out. When the AST1 electromagnetic valve 1 or the AST3 electromagnetic valve 3 is powered off, the ASP pressure is increased to be more than 1.5MPa, and the first group of ASP pressure switches 15 send out information; when either the AST2 solenoid valve 2 or the AST4 solenoid valve 4 is de-energized, the ASP pressure should drop below 0.5MPa and the second set of ASP pressure switches 15 will signal.

An inlet orifice 17 is provided between the first unloading valve 5 and the third unloading valve 7 and the emergency stop test line (ASP), and an outlet orifice 18 is provided between the emergency stop test line (ASP) and the pressureless return line 9.

Example two

As shown in fig. 2 to 7, in the present embodiment, the valve block 19 is included, and the AST1 solenoid valve 1 and the AST3 solenoid valve 3 are integrally mounted on the same side of the top end of the valve block 19, and the AST2 solenoid valve 2 and the AST4 solenoid valve 4 are mounted on the other side of the top end of the valve block 19.

An AST safety oil path (AST), a pressure oil path, an emergency stop test pipeline (ASP) and a pressureless oil return pipeline 9 are all arranged in a valve block 19, and each unloading valve is arranged in the valve block 19, wherein a first unloading valve 5 is connected with an AST1 electromagnetic valve 1 through a pipeline, a second unloading valve 6 is connected with an AST2 electromagnetic valve 2 through a pipeline, a third unloading valve 7 is connected with an AST3 electromagnetic valve 3 through a pipeline, and a fourth unloading valve 8 is connected with an AST4 electromagnetic valve 4 through a pipeline.

An AST connecting hole and an ASP connecting hole are formed in the top of the valve block 19, screw plugs 23 are arranged outside the AST connecting hole and the ASP connecting hole, and non-pressure oil return holes DV1 and DV2 communicated with the non-pressure oil return pipeline 9 are formed in the side face of the valve block 19. The AST1 electromagnetic valve 1 and the AST3 electromagnetic valve 3 are respectively connected with an emergency stop test pipeline (ASP) which is arranged in the valve block 19 through a first unloading valve 5 and a third unloading valve 7, a valve, an ASP pressure switch and an ASP pressure gauge can be externally connected through an ASP connecting hole, an inlet orifice 17, a damping element 20 and a process plug 21 are sequentially connected between the first unloading valve 5 and the third unloading valve 7 and the ASP connecting hole, and the opening and closing size of the inlet orifice 17 is adjusted by the system pressure.

The AST1 solenoid valve 1 and the AST3 solenoid valve 3 are connected with an AST safety oil passage (AST) which is opened in the valve block 19 through a first unloading valve 5 and a third unloading valve 7 respectively, and the AST safety oil passage is connected with external electric elements such as a multi-way AST pressure switch 11, an AST pressure gauge 12, a stop valve 13 and the like through an AST connecting hole which is arranged at the top of the valve block 19.

The AST2 electromagnetic valve 2 and the AST4 electromagnetic valve 4 are respectively connected with a DV1 process port and a DV2 process port of a non-pressure oil return pipeline 9 arranged in a valve block 19 through a second unloading valve 6 and a fourth unloading valve 8, an outlet orifice 18, a damping element 20 and a process plug 21 are arranged between the second unloading valve 6 and the fourth unloading valve 8 and between the second unloading valve 8 and the DV2, the opening and closing size of the outlet orifice 18 is regulated by the system pressure, and a pressure plug 22 is arranged outside the process plug 21. When no electrical component is externally connected, the press plug 22 is in an installed state.

The present embodiment embodies the control device of embodiment one by means of the valve block 19 and the various lines and connected components provided therein, the control logic of which is the same as that of embodiment one.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present utility model, and not for limiting the same; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the utility model.

Claims (10)

1. A steam turbine emergency shutdown device, comprising: the system comprises an AST safety oil circuit, a pressure oil circuit, four AST electromagnetic valves, four unloading valves and an emergency stop test pipeline, wherein an AST1 electromagnetic valve and an AST3 electromagnetic valve are arranged in parallel, oil inlets of the AST1 electromagnetic valve and the AST3 electromagnetic valve are respectively connected with the pressure oil circuit, a working port of the AST1 electromagnetic valve is connected with a first unloading valve in series, a working port of the AST3 electromagnetic valve and a third unloading valve are connected with each other in series, and two ports of the first unloading valve and the third unloading valve are respectively connected with the AST safety oil circuit and the emergency stop test pipeline;

An AST2 electromagnetic valve and an AST4 electromagnetic valve are arranged in parallel, oil inlets of the AST2 electromagnetic valve and the AST4 electromagnetic valve are respectively connected with the pressure oil path, a working port of the AST2 electromagnetic valve and a second unloading valve are connected in series, a working port of the AST4 electromagnetic valve and a fourth unloading valve are connected in series, two ports of the second unloading valve and the fourth unloading valve are respectively connected with the pressure oil path and the emergency stop test pipeline, and the AST1 electromagnetic valve and the AST3 electromagnetic valve which are connected in parallel are connected with the second unloading valve and the fourth unloading valve through non-pressure oil return pipelines;

When the four AST electromagnetic valves are electrified, pressure oil enters the unloading valve connected with the pressure oil passage through each AST electromagnetic valve from the pressure oil passage, so that the unloading valve is closed, the AST safety oil passage is prevented from unloading, AST oil pressure is built, the unit is in a hanging state, and a main valve and an adjusting valve can be opened;

When at least one of the AST1 electromagnetic valve and the AST3 electromagnetic valve and at least one of the AST2 electromagnetic valve and the AST4 electromagnetic valve are controlled by a steam turbine stopping signal to be in power-off and closed, the unloading valve connected with the unloading valve acts, the AST safety oil way discharges oil through an AST oil discharge channel, the unit is in a switching-on state, and the main valve and the regulating valve are closed.

2. The steam turbine emergency shutdown device of claim 1, wherein the emergency shutdown test line is provided with two sets of ASP pressure switches for monitoring ASP oil pressure.

3. The steam turbine emergency shutdown device of claim 2, wherein an ASP pressure gauge is connected in parallel to one side of the ASP pressure switch.

4. A steam turbine emergency shutdown device as claimed in claim 3, wherein each of the ASP pressure switches and each of the ASP pressure gauges are connected to at least one shut-off valve.

5. The steam turbine emergency shutdown device of claim 1, wherein four sets of AST pressure switches and a set of AST pressure gauges are connected to the AST drain line for monitoring AST oil pressure.

6. The steam turbine emergency shutdown device of claim 5, wherein each of the AST pressure switch and the AST pressure gauge is connected to at least one shut-off valve, and the AST pressure gauge is connected to a pilot operated check valve.

7. The steam turbine emergency shutdown device according to claim 1, wherein an inlet orifice is provided between the first unloading valve and the third unloading valve and the emergency shutdown test line, and an outlet orifice is provided between the emergency shutdown test line and the pressureless return line.

8. The steam turbine emergency shutdown device of claim 7, further comprising a valve block, wherein the AST1 solenoid valve and the AST3 solenoid valve are mounted on a same side of a top end of the valve block, and wherein the AST2 solenoid valve and the AST4 solenoid valve are mounted on a same side of a bottom end of the valve block.

9. The steam turbine emergency shutdown device according to claim 8, wherein the AST safety oil passage, the pressure oil passage, the emergency shutdown test line, and the pressureless return line are all opened in the valve block, the unloading valves are installed in the valve block, and opening and closing sizes of the inlet orifice and the outlet orifice are adjusted by a system pressure.

10. The steam turbine emergency shutdown device of claim 9, wherein an AST port and an ASP port are provided on a front surface of the valve block, and a non-pressure oil return hole communicating with a non-pressure oil return line is provided on a side surface of the valve block.