High Speed PV Valve

For some special chemicals, there are some special requirements during the loading process and during the sailing process. Some are required to achieve zero leakage during the voyage after loading according to the regulations.  

DF-ISO type high-speed PV venting valve can meet the requirement of zero leakage after the forced closing device is installed.

Of course, the forced shut-off device can also be used to cope with any special situation that needs to be turned off.

1. The high speed PV valve with different types 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.

The standardized flange of the high-velocity relief valve is connected with the pipe flange of the cargo oil tank, and the mixed compressed gas will be formed when the cargo oil tank is loading cargoes. The valve on the pressure valve with the block will spring out in a flash, at the same time the valve will open while the pressure of the compressed gas reaches to the set pressure (the oil tank is 14KPa, chemical tank is 20KPa), then releasing the mixed compressed gas to the air with the speed of more than 30m/s (it will be more then 30m/s under the regular operation).

The vacuum will be formed while the cargo oil is tank unloading. the valve will open automatically while the vacuum reaches to the set pressure (it is -3.5KPa), and then the air will go into the tank through the flame screen.

If the pressure is too high while the ship is sailing, the high-velocity relief valve will automatically release the pressure and balance it.

The Pressure-Graph of Pressure Valve 

The Pressure-Graph of Vacuum Valve

The simulant loading and unloading tests shall be done on each graph of the pressure valve according to the operation pressure which provide by Ship Desing & Research Institute, then provide the following graph and flow datum under different pressure to the ship-owner.

Pressure operation testing shall be done on each DF-ISO high-velocity relief valve, make sure it can be operated smoothly during the process of increasing or decreasing the pressure.

As the above-mentioned, assemble the pressure/vacuum valve with different specifications on the ship according to its loading rate, ensure the pressure of the tank is under the specific working pressure, then the pressure valve and vacuum valve will work smoothly no matter the pressure increases or decreases.

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