Pressure Vacuum relief Valve

Pressure Vacuum Relief Valve with Gas Freeing Cover

The Pressure Vacuum relief Valve for cargo ships is also called high velocity relief valve or P/V valve.
  • Material:  Carbon Stee, SUS 304/304L/316L
  • Sizes: DN50-DN250
  • Features: With Gas Freeing Cover
  • Certificate: CCS/ABS/EC


Pressure Vacuum Relief Valve with gas freeing cover is same function with the basic DF-ISO high velocity relief valve , but added a gas freeing cover. 

The purpose of the gas freeing cover is to open the Pressure Valve manually, because the pressure valve could be only automatically opened when the tanker reach to the setting pressure. But for other jobs, like cleaning, exhausting, the tanker should be also ventilated, the gas freeing cover is used in this situation. 

It is eqiupped with the V part of the pressure vacuum valve, or it can be equipped with branch pipe of the high velocity relief valve. 

According to the regulations of MSC/Circ 677, the gas-freeing cover can prevent the flame into the tank . 

Technical Data

1. The Pressure Vacuum Relief Valve with different specifications have the same diameter and performance parameter;
2. The opening pressure of the vacuum valves are -3.5kPa, the opening pressure of the pressure valves for the oil tank is 14kPa, but for the chemical tank is 20kPa. The opening pressure of the pressure may be different, but the differences of opening pressure and flow range is inapparent if the pressure valves have the same diameter.

spec. of high velocity pv valve

Installation Diagram

If the ship Design & Research Institutes or ship-owners want to assemble both gas-freeing cover and some other accessories on the pressure vacuum relief valve, then the gas-freeing cover can fix on the branch of vent pipe. 

How to install the pressure vacuum valve

Structure of Pressure Vacuum Relief Valve

The gas freeing cover is consist of the shell, the upper cover and flame screen (flame retardant bed).  It can directly assemble on the vacuum valve of the pressure vacuum relief valve. 

sturecutre of pressure vacuum relief valve