4636 results about "Check valve" patented technology

Embodiments of a manifold of a hydraulic fracturing system include a junction having an inlet flow bore. The junction can include an integrated flow junction and valve check assembly having a body including a central portion and one or more side portions. The central portion can be positioned between a pair of manifold sections of the manifold and attached thereto. The one or more side portions extend radially from the central portion and include an inlet bore through which a pressurized fluid is received and supplied to the manifold. One or more check valves is positioned along the inlet bore so as to be integrated within the body of the junction.

A water flosser with a unidirectional sealing device includes a shell and a second check valve. A water storage chamber and a liquid outlet communicated to the water storage chamber are provided inside the shell. The liquid outlet is arranged at a bottom of the water storage chamber. The shell downwards extends along an edge of the liquid outlet to form a first abutment block. A protruding second abutment block is arranged in the shell; the second abutment block is arranged towards the first abutment block. The second check valve is provided with an abutment board. The first abutment block abuts against an upper surface of the abutment board. The second abutment block abuts against a lower surface of the abutment board, to limit the second check valve between the first abutment block and the second abutment block.

The invention relates to the technical field of hydrogen storage system testing, and discloses a one-way valve combined hydrogen storage system durability test bench and a test method. A main control computer of the rack is used for configuring test task parameters, coordinating operation of subsystems and processing test data; the high-pressure hydrogen supply subsystem comprises a pressure-adjustable hydrogen source and a pressure closed-loop control module, and can apply accurate and controllable hydrogen pressure to the inlet end of the tested system according to test task parameters; the multi-channel valve state acquisition subsystem acquires the inlet and outlet pressure of the valve, the surface temperature of the valve body and vibration spectrum data in real time through pressure, temperature and vibration sensor arrays arranged at the valves, and transmits the data to the main control computer; the valve action driving subsystem comprises a high-speed electromagnetic actuator array and a displacement feedback module and can drive all valves to execute a preset opening degree sequence and opening and closing frequency. And the durability evaluation subsystem is embedded into the main control computer, calculates the accumulated damage degree of the valve and predicts the residual life cycle.

The invention belongs to the field of hydrogen filling, and relates to an automatic hydrogen filling system for a hydrogenation mother station, which comprises a hydrogen purification device, a plurality of hydrogen compressors, a plurality of filling main pipes, a plurality of branch pipelines, a plurality of emptying pipelines, a plurality of filling hoses and a control system, an outlet of each hydrogen compressor is connected with a compressor outlet pressure gauge and a check valve, each branch pipeline is provided with a branch stop valve, and each emptying pipeline is provided with an emptying adjusting valve. And the control system is in signal connection with the compressor outlet pressure gauge, the branch stop valve, the emptying regulating valve and a long pipe vehicle pressure gauge arranged on the long pipe vehicle, and is used for automatically executing the actions of boosting, depressurizing, filling and stopping filling according to the pressure difference. Compressor pressure, filling header pipe pressure and long pipe vehicle pressure cooperate with one another, full automation and full flow of filling boosting and depressurization are achieved, and the working efficiency is improved.

A check valve assembly can include a housing including an inlet port, an outlet port, and a flow chamber defined by the housing and fluidly coupling the inlet port to the outlet port, an actuation chamber, and a piston assembly movable between a closed position and an open position. The piston assembly can include a poppet positioned in the flow chamber and can be configured to sealingly engage the housing in the closed position to fluidly separate the inlet port from the outlet port, and a flange positioned in the actuation chamber. The flange can contain a sealing member positioned between the flange and the housing to fluidly separate a forward actuation chamber from a rearward actuation chamber. A shaft can extend between the poppet and the flange. A biasing member can be operably coupled to the piston assembly wherein the biasing member biases the poppet assembly closed.

The utility model discloses a semi-automatic backwashing laminated filter. The external structure of the semi-automatic backwashing laminated filter comprises a handle, a filter base body, a water inlet, a water outlet, a laminated shell, a blow-down valve, a blockage indicator, a filter screen flushing valve and the like, the internal structure comprises a flow direction selector, a butterfly check valve, a laminated filter element, a rotational flow centrifugal disc, a laminated compression inner cover, a laminated compression outer cover, a spring between the laminated compression inner cover and the laminated compression outer cover and the like. The channel position of the flow direction selector is switched by rotating the handle, so that the switching between the filtering mode and the backwashing mode is realized. In a filtering mode, muddy water flows into a raw water cavity outside the lamination after being accelerated by the rotational flow centrifugal disc, impurities are intercepted, and clear water flows into a downstream pipeline; and in a backwashing mode, the water flow is sprayed out from the spraying holes in the filter element frame by pressing the position of the lamination for compressing the inner cover and loosening the lamination, so that impurities are eluted from the lamination and discharged through the blow-down valve. In addition, a filter screen is arranged on the flow direction selector to intercept impurities of flushing water, and the filter screen can be flushed in a filtering mode. The utility model has the advantages of convenient use and simple structure.

The invention relates to the technical field of valves, in particular to a duplex check valve. Comprising a valve body, a circulation opening formed in the valve body, a valve seat arranged on the valve body and located in the circulation opening, a first through hole formed in the valve seat, a sealing valve clack arranged in the valve body in a lifting mode, a guiding piece arranged between the valve seat and the sealing valve clack, and a compression spring arranged between the guiding piece and the sealing valve clack. The auxiliary sleeve is arranged on the valve body and located at the circulation opening, the second through hole is formed in the valve body, the auxiliary valve clack is arranged on the valve body in a lifting mode and located in the circulation opening, the lower end of the auxiliary guide rod is fixedly arranged on the sealing valve clack, the linkage shaft is arranged at the lower end of the sealing valve clack and located in the auxiliary sleeve, and the lower end of the linkage shaft makes contact with the upper end of the auxiliary guide rod. Through the design of the double valve clacks, the double-sealing effect is achieved, the reliability and the sealing performance of the check valve are improved, the linkage shaft structure ensures that the main valve clack and the auxiliary valve clack move synchronously, and response is rapid.

The utility model discloses a hydraulic logic control system for a sidesway distance adjusting fork. Comprising an oil pump, a safety valve, a first reversing valve plate, a logic control valve block, a first hydraulic control one-way valve, a first three-way pipe, a right pallet fork distance adjusting oil cylinder, a left pallet fork distance adjusting oil cylinder, a first overload valve, a second hydraulic control one-way valve, a second three-way pipe, a third three-way pipe, a third hydraulic control one-way valve, a throttling valve, a second reversing valve plate and a second overload valve. The logic control valve block comprises a second hydraulic control one-way valve, a third hydraulic control one-way valve, a throttling valve and a second overload valve, and the second hydraulic control one-way valve, the third hydraulic control one-way valve, the throttling valve and the second overload valve are communicated through pipelines. And the first reversing valve plate is communicated with the second reversing valve plate. According to the hydraulic logic control system for the laterally-moving distance adjusting fork, the purpose of hydraulic oil way regulation and control is achieved through the arrangement of the structure.

The invention discloses an oil way structure of a hydraulic damping cylinder, the hydraulic damping cylinder, a limb and a robot, and the oil way structure of the hydraulic damping cylinder comprises a body which is provided with a first group of one-way valve mounting positions, a second group of one-way valve mounting positions, a damper mounting position and a hydraulic cylinder mounting position; a first one-way valve and a second one-way valve are mounted at the first one-way valve mounting A third one-way valve and a fourth one-way valve are mounted at the second one-way valve mounting A first channel, a second channel, a third channel, a fourth channel and an intersection channel are formed in the body. Relative to the intersection channel, the first one-way valve, the second one-way valve, the third one-way valve and the fourth one-way valve have the same flowing direction. And the oil path structure forms a channel for hydraulic oil to circulate, so that the hydraulic oil circulates in each component of the hydraulic damping cylinder. According to the oil way structure of the hydraulic damping cylinder, hydraulic oil channels are concentrated, the number of the hydraulic oil circulation channels in other parts of the hydraulic damping cylinder is reduced, and the overall machining difficulty and cost of the hydraulic damping cylinder are reduced.

The invention provides an anti-surge and anti-backflow control method for a magnetic suspension air blower, and belongs to the technical field of air blowers. The anti-surge and anti-backflow control method for the magnetic suspension air blower comprises the steps that an electric check valve is arranged in an air supply pipeline outside fan equipment, and the electric check valve is electrically connected with a system corresponding to the magnetic suspension air blower; a plurality of rotating speed gears are divided in a low-speed operation interval of the fan, different rotating speed gears correspond to different opening degrees of the electric check valve, and the larger the rotating speed is, the larger the opening degree of the corresponding electric check valve is; the fan enters a low-speed operation interval after being started, the rotating speed gear of the motor is adjusted step by step from small to large, and the system correspondingly adjusts the opening degree of the electric check valve according to the rotating speed gear where the motor is located; and after the fan enters the high-speed operation interval, the electric check valve is fully opened, and the speed is directly increased to the target set rotating speed. According to the anti-surge and anti-backflow control method for the magnetic suspension air blower, the surge inducement of sudden pressure rise caused by closing of the electric check valve is avoided.

A milling bit is disclosed for debris collection within a wellbore. A check valve can be part of a debris removal tool that includes a motor, a pump, a gearbox, a bailer, the milling bit, and rotational shafts. In an example, on its uphole end, the milling bit can be coupled with the check valve. On its downhole end, the milling bit can be configured for debris removal with cutting edges. The downhole end can also include openings that provide access to an internal cavity of the milling bit. The internal cavity can extend the entire length of the milling bit. This allows the pump to pull drilling fluid into the bailers through the milling bit and check valve. As a result, the debris removal tool can simultaneously remove obstructions in a wellbore and collect debris from the obstruction removal.

The device for varying the incline of photovoltaic power generation inclination by using fluid thermal expansion of the present invention comprises a thermal expansion cylinder device and an automatic deviation correction device for simultaneously correcting deviations of the height and inclination angle of a photovoltaic panel. The thermal expansion cylinder device is composed of a thermal expansion fluid, a main piston, and a cylinder. The cylinder interior is filled with the thermal expansion fluid, the volume of which expands or contracts according to the temperature, thereby moving the main piston in the longitudinal direction. The linear displacement of the thermal expansion cylinder device installed between the photovoltaic panel and a fixed structure contracts when the ambient temperature is low (for example, winter solstice), thereby increasing the angle of inclination of the photovoltaic panel, and the linear displacement of the thermal expansion cylinder device expands when the temperature is high (for example, summer solstice), thereby lowering the angle of inclination of the photovoltaic panel. The automatic deviation correction device comprises an expanded volume accommodation device, a spring, an auxiliary piston, a check valve, and a pushrod. The forward movement length of the main piston is limited after summer solstice when the upper limit setting value is set. The check valve is opened by the thermal expansion fluid pressure such that the fluid flows into an excess expanded volume accommodation device. The auxiliary piston moves backward and compresses the spring, and when the temperature descends again after the highest temperature has been reached, the check valve is closed by the spring elastic force and pressure deviation.

The invention relates to the technical field of check valves, in particular to a butterfly check valve with opening indication, which comprises a valve body, a transmission gear and a frame body are respectively arranged on the surface and the top of a right-angle part of an L-shaped mounting groove of the valve body, and a screw rod transmission mechanism on the inner wall of the frame body is respectively connected with the transmission gear and a strip-shaped sliding seat which is horizontally and slidably connected to the top of the frame body; a mechanical opening indicating mechanism; and a sensing indication mechanism is integrated. Opening, flow, pressure and sealing states can be detected synchronously, mechanical indication and electronic sensing are combined, electricity-free use and digital reading are both considered, and misjudgment is reduced through the multi-redundancy design; the transparent observation plate and the modular structure are convenient to operate and maintain, and the liquid collection and drainage design prevents interference of condensate water; the flowmeter wear-resistant ceramic probe and the pressure sensor moisture-proof shell are adaptive to complex working conditions; backflow can be effectively recognized through bidirectional flow detection and triple sealing verification, the safety redundancy of a system is greatly improved, and the problems that a traditional check valve is single in function and insufficient in reliability are solved.

A sound-recognition-based method for monitoring an operating condition abnormity of an oil pump electric motor and outlet pipes thereof. Applying soundprint recognition technology to a speed-regulating hydraulic system of a hydropower station, and rational layout of on-site soundprint sensors realize real-time monitoring of operating conditions of an oil pump electric motor and outlet pipes thereof, thereby improving the intelligence level of device management, and achieving an industrial demonstration effect. By means of deep learning analysis of a soundprint fault sample library combined with multi-dimensional factors such as pressure, liquid level and temperature, a soundprint-recognition-based multi-dimensional-factor logical determination process for abnormal operating conditions of an oil pump electric motor and outlet pipes is designed, such that real-time monitoring and rapid locating of abnormal operating conditions such as base vibration, lubricating oil deficiency in an oil pump electric motor, pump body blade fracture, check valve malfunction, incomplete closure or internal leakage of a drain valve, frequent loading and unloading of an oil pump, and servomotor pipe pulsation are realized, so as to promptly use response measures such as automatic switching of main and standby oil pump electric motor units or automatic adjustment of unit load. Using soundprint sensors and soundprint recognition technology to monitor the state of on-site devices in real time eliminates uncertainties in manual inspection, and improves the fault diagnosis and analysis efficiency.

A hydraulic circuit includes a first oil path, a second oil path, a hydraulic control circuit, a third oil path, a check valve, and a relief valve. The first oil path links to a discharge port of a first oil pump. The second oil path links to a discharge port of a second oil pump. In the hydraulic control circuit, a first regulator valve is disposed downstream of a confluence point of the first oil path and the second oil path. The third oil path connects a suction port of the first oil pump and a strainer. The check valve is provided in the third oil path and restricts a movement of oil toward the strainer side. The relief valve is provided in the third oil path and discharges oil in the third oil path to an outside when a pressure in the third oil path exceeds a reference pressure.

The application provides a tunnel advanced small catheter and a grouting method thereof, which comprises an advanced small catheter body, a grouting pipe arranged in the inside of the advanced small catheter body, the outer diameter of the grouting pipe is smaller than the inner diameter of the advanced small catheter body, a piston is detachably installed on the front end of the grouting pipe, the piston is sealed and blocked in the inside of the advanced small catheter body, a plurality of grouting holes are arranged on the front end of the piston, the grouting holes are communicated with the grouting pipe, a check valve is arranged in the inside of the piston for controlling the opening and closing of the grouting holes, a limiting device for preventing the piston from being taken out is arranged on the inner wall of the rear end of the advanced small catheter body, and the grouting pipe can pass out of the limiting device. The grouting uniformity is good, the slurry can be gradually and uniformly filled from the hole bottom to the hole opening during grouting, the problem of local grouting insufficiency in the traditional grouting method is avoided, the reinforcement effect of the surrounding rock is effectively improved, and the stability and safety of the tunnel are enhanced.

The utility model provides an artificial insemination tube assembly, which belongs to the technical field of insemination tubes and comprises a storage tube, a push rod and an annular air bag, the push rod and the annular air bag are arranged on the storage tube, a feeding tube is arranged on the side wall of one end of the storage tube, and a seminiferous duct is mounted at one end of the storage tube. According to the insemination device, the annular air bag arranged on the outer side of the seminiferous duct expands while insemination is conducted, it is guaranteed that the device is fixed, meanwhile, the situation that semen flows back after insemination is effectively prevented, and then the probability of pregnancy is improved, meanwhile, two one-way valves are installed on the two sides of the annular air bag, and after the annular air bag completely abuts against the inner wall of a uterine cavity, the two one-way valves are closed. When the device is taken out, the other one-way valve is forced to be opened and closed to supplement air into the annular air bag from the outside in the subsequent process of taking out the device, so that the push plug is convenient to move to the initial position, and the safety of the device is improved. The subsequent addition and use of the seminal fluid are convenient.

The shock absorber with the negative stiffness characteristic comprises a cylinder barrel, a piston rod, a piston and a bottom valve, a stretching valve and a one-way valve are arranged on the piston, a compression valve and a one-way valve are arranged on the bottom valve, a valve element of the compression valve is connected to a valve element of the stretching valve through a spring, and a limiting device of the valve element of the stretching valve is arranged on the piston or the piston rod. Damping force values of the compression valve and the stretching valve are both controlled by the stroke of the piston and the acting force of the spring. In the stretching process of the shock absorber, when the spring is in a pressed state, the stretching valve forms damping force, and the shock absorption effect is achieved. The larger the compression stroke (compression force value) of the spring is, the larger the tensile damping value of the shock absorber is. In the compression process of the shock absorber, when the spring is in a pulled state, the compression valve forms damping force, and the shock absorption effect is achieved. The larger the stretching stroke (stretching force value) of the spring is, the larger the compression damping value of the shock absorber is.

The invention relates to a chemical aging device comprising an enclosure inside which are installed a plurality of test receptacles (16), each test receptacle containing a certain amount of aqueous solution (18) and a membrane sample (12), each test receptacle (16) being equipped with a gas and vapour evacuation duct (22) connected to its internal volume, the various evacuation ducts (22) of the various test receptacles (16) being connected to a gas and vapour extraction duct (24), this extraction duct (24) passing through a wall of the closed enclosure, this extraction duct (24) being connected to a container flask (26), situated outside the closed enclosure, and opening into a buffer solution (28) contained in this container flask, at least one check valve (32) equipping each evacuation duct, and the chemical aging device comprising an agitation device (34) for agitating the test receptacles.

The invention discloses a testing device and a testing method for a vertical valve, and relates to the technical field of valve detection.The testing device comprises a bearing mechanism, two lower testing mechanisms are arranged at the bottom of the inner side of the bearing mechanism, and upper testing mechanisms located over the adjacent lower testing mechanisms are arranged at the top of the inner side of the bearing mechanism; the left side of the upper test mechanism is provided with an up-down traction mechanism, and the inner side of the up-down traction mechanism is in transmission connection with a push-pull mechanism which is in transmission connection with the left side of the adjacent lower test mechanism. The up-down traction mechanism comprises an extension plate fixedly arranged on the left side of the sealing cover, a traction sleeve is slidably arranged on the inner side of the extension plate in the vertical direction, and an annular limiting groove is formed in the middle of the outer side of the traction sleeve. According to the invention, the time interval between two adjacent test operations can be effectively shortened while the taking and placing difficulty of the tested check valve is reduced, so that the overall test efficiency is improved, and the method is suitable for continuous tests of valve manufacturers.

A break check valve can include one or more rotating members configured to rotate to alter the break check valve from an open position to a closed position upon dislocation of a pipe system fitting, the break check valve being altered from an open position to a closed position when acted upon by fluid within a piping system.

The invention belongs to the technical field of pipeline valves, and particularly relates to a resistance-free prevention valve. Comprising a discharge valve, a main valve and two check valves, and the two check valves are fixedly installed in an inner cavity of the main valve and divide the inner cavity of the main valve into an inlet cavity, a middle cavity and an outlet cavity. When the pressure difference between the inlet cavity and the middle cavity is larger than a set value, the discharge valve is closed, and when the pressure difference between the inlet cavity and the middle cavity is continuously smaller than the set value, the pressure difference discharge valve is opened, discharge and pressure reduction are conducted through the discharge channel, and the discharge valve is closed until the pressure difference between the inlet cavity and the middle cavity recovers to the set value; the anti-misoperation device is arranged in the discharge valve, so that misoperation discharge of the discharge valve caused by water pressure fluctuation in a pipeline can be effectively prevented, and water pressure loss is avoided; valve membrane abrasion is reduced, and the service life of the discharge valve is prolonged; and the pressure difference during drainage can be adjusted according to working conditions and requirements.

The invention relates to an industrial wastewater treatment system and method. The system comprises a waste liquid leading-out pipeline, and a waste heat utilization device, a physical removal module, a chemical detection module and a biological deep purification module are sequentially arranged along the waste liquid leading-out pipeline. A control valve and a check valve are arranged between the waste heat utilization device and the physical removal module and are used for controlling the volume of waste liquid in the physical removal module; a power pump II, a second filter and a three-way valve I are arranged between the physical removal module and the chemical detection module and are used for further removing residual particulate matters in the wastewater; the output end of the chemical detection module is used for guiding the preliminarily screened wastewater to the biological deep purification module through a water quality detector I and a three-way valve II. The method effectively solves the problems of low efficiency, high cost, incomplete pollutant removal and the like in the existing wastewater treatment technology, realizes efficient recovery and reutilization of wastewater, reduces the energy consumption and cost of wastewater treatment, and has important environmental protection and economic values.

A hydraulic system of a windrower includes a hydraulic pressure source of a higher pressure hydraulic fluid and a hydraulic pressure return for receiving lower pressure hydraulic fluid. A parking brake is configured to be released by application of the higher pressure hydraulic fluid. A hydraulic fluid supply line is communicated with the parking brake. An electrically operated hydraulic fluid supply valve communicates the supply line with the hydraulic pressure source or with the hydraulic pressure return. An electrically operated selectable check valve is disposed in the supply line between the supply valve and the parking brake, the check valve being shiftable between a checking position permitting hydraulic fluid flow from the supply valve to the parking brake and preventing hydraulic fluid flow from the parking brake to the supply valve, and an open position communicating the supply valve with the parking brake.

The invention discloses a preparation device and process of hydrophobic lightweight concrete, and relates to the technical field of concrete processing, the preparation device comprises a base, a pedestal, a die holder, a vibration mechanism, a pressing plate, a hydraulic cylinder, a height adjusting mechanism and a one-way valve structure; the height adjusting mechanism communicates with the exhaust channel and is configured to drive the pressing plate to descend relative to the hydraulic cylinder through the pressure of gas entering the exhaust channel so as to reduce the distance between the pressing plate and the upper surface of the raw material. According to the invention, the special one-way valve structure is arranged on the pressing plate and matched with the up-and-down reciprocating motion of the die holder, so that air extruded from raw materials can be actively exhausted to the exhaust channel in the vibration process, and most of air can be effectively exhausted even if the vibration time is relatively short, so that the tap density of the raw materials is ensured, and the production efficiency is improved. And the layering phenomenon of light and heavy materials caused by long-time vibration is avoided, so that the overall quality and the yield of the lightweight concrete are remarkably improved.

A magnetic non-return valve having a valve body and a valve housing arrangement, wherein the valve body is guided so as to be axially displaceable in the valve housing arrangement and closes the fluid duct of the valve housing arrangement by way of a holding force acting counter to the direction of flow, wherein the axial holding force is generated by a repelling magnet arrangement, wherein a concentric piston connected to the valve body via the end face comprises a first magnet arrangement and the valve body guide comprises a second magnet arrangement, wherein the first magnet arrangement is arranged in a cavity of the piston and is enclosed so as to be media-tight on all sides, and the second magnet arrangement is arranged in a cavity of the valve body guide and is enclosed so as to be media-tight on all sides.

The utility model provides an oil separator which comprises a barrel, an air inlet pipe, an oil return pipe, an air outlet pipe and a one-way valve. The air inlet pipe and the oil return pipe are connected to the barrel. The air outlet pipe is connected to the cylinder, one end of the air outlet pipe extends into the cylinder, and the other end of the air outlet pipe extends out of the cylinder. The one-way valve is arranged at the end, located in the cylinder, of the air outlet pipe and used for limiting the medium of the air outlet pipe to only flow out of the cylinder, and the one-way valve is a diaphragm type one-way valve. By means of the structural design, the reverse non-return function on the gas outlet passage of the oil separator is achieved through the diaphragm type one-way valve, media such as gas of an external pipeline are prevented from flowing into the barrel through the gas outlet pipe, the reverse flow phenomenon is avoided, and the stability and reliability of the oil separator are improved.

Belonging to the field of marine resource exploration equipment, the invention relates to a portable pressure maintaining gravity sampler, which comprises an extraction hole, an empennage, a counterweight, a connecting piece, a control piece, a large spring, a control mechanism shell, a positioning block, a release pipe, a small spring, a spacer pin, a sliding pipe, a pressure maintaining pipe, a closed ring, a mandrel, a flap valve, a check valve ball, a sampling pipe, a one-way flap, a tool bit, a drain hole, a limiter and a pipe body. According to the design scheme, the sampler is provided, through the design of the control mechanism shell, the pressure maintaining pipe and the sampling pipe, a light-weight pressure maintaining structure is provided, and complex pressure compensation or a hydraulic system is not needed; in addition, a sealing and pressure maintaining device is optimized, the in-situ pressure of the seabed sediment can be stably maintained so as to guarantee the integrity of the sample, meanwhile, the operation process of the sampling process is simplified, the manufacturing cost and the fault risk are reduced, and the dual requirements of marine geological research, mineral resource exploration and other scenes for high-quality samples and efficient operation are met.

The utility model discloses an ammonia fuel low-speed engine test bed security system which comprises a plurality of two-way electromagnetic valves, a plurality of one-way valves, a plurality of pressure sensors, an air supply fan, an air draft fan, a manual two-way valve, a buffer tank, an ammonia detector, a three-way electromagnetic valve, a flow meter and an outdoor ammonia steam tank. And a signal line of the PLC is respectively connected with the control ends of the two-way electromagnetic valves, the pressure sensors, the air supply fan, the air draft fan and the flow meter. Under different working conditions of slight leakage or serious leakage of ammonia fuel, the leaked ammonia fuel is recovered into the outdoor ammonia evaporation tank, so that the safety of field personnel is ensured, and a reliable guarantee is provided for safe and reliable test run of the ammonia fuel low-speed engine.

The present disclosure relates to a check valve (1) comprising: a valve housing (10); a valve member (11) within the housing, the valve member being movable between an open position and a closed position; and at least one restricted channel (14) through the valve member, wherein, in the closed position, the at least one restricted channel is arranged to allow a restricted backflow of fluid through the valve. The present disclosure also relates to a system comprising: an electrochemical device and the check valve, wherein the check valve is connected to an outlet pipeline of the electrochemical device.