• TJ-12

2step open emergency shutoff valve

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Product Detail

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Technical parameters

  • Nominal pressure: 2.8MPa
  • Applicable temperature:-50℃ ~+120°c
  • Test pressure: 4.2MPa
  • Applicable medium: ammonia, fluorine, propane,etc.


  • QDJ421F28-2W is a two-step opening emergency shut-off valve made of one main valve AM3+ piston assembly and two solenoid pilot valves aevm (NC).
  • With manual closing and opening functions.

Operation principle

  • First open the a solenoid pilot valve, and the medium enters the top of the upper piston Push the piston and drive the lower piston to move downward The valve is opened by about 10% (it can buffer and balance the internal pressure in the high-pressure liquid pipeline, prevent the liquid from generating liquid hammer in the valve body when the valve is opened, and reduce the instantaneous vibration of the pipeline when the valve is opened)
  • B after the solenoid pilot valve is delayed to open The medium enters the top of the lower piston and continues to push the lower piston downward until the valve is fully opened. In case of emergency. At the same time, cut off the power supply of AB solenoid pilot valve The piston is under the action of spring force. Lower piston moves up lower part of upper piston And drive the upper piston to move upward until the valve is closed.


It is mainly used in the outlet pipeline of high-pressure liquid storage tank. PLC or remote control operation is used to control the power supply of solenoid pilot valve coil to close the main valve. Thus, the medium flow in the pipeline can be quickly cut off. It can provide safety protection in case of emergency.

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