HB802X-80 Series Stainless Steel Exhaust Safety Valves – Protect Your Chemical Storage Tanks

They are usually to be installed on the top of the chemical liquid tank tank, with the function of releasing the emergency pressure. 

Have following 3 items with different founctions:

HB802A-80

HB802B-80

HB802C-80

HB802A-80 is a One Way Exhaust Vent Valve with only one pressure valve disc. When the tank's internal pressure is higher than the rated releasing pressure, the valve disc will be open and release the extra pressure.

HB802B-80 is a Vacuum Pressure Vent Valve with two valve discs, one of which is a pressure valve disc, and the other is a vacuum valve disc. When the liquid vapor pressure in the tank exceeds the allowable pressure, the vapor is released through the pressure valve, while the vacuum valve disc remains closed. When the liquid vapor pressure in the tank is lower than the allowable vacuum, fresh air enters the tank through the vacuum valve disc, while the pressure valve disc remains closed.

HB802C-80 is a one-way exhaust vent valve with one pressure valve disc and an additional bursting disc device ( a pressure relief device which couldn’t be closed after bursting under a set pressure). After bursting, the bursting disc needs to be replaced. When the tank internal pressure is higher than the rated burst releasing pressure, the bursting disc will be destroyed, and the pressure valve disc will open and release the extra pressure. The bursting pressure of the bursting disc is usually 0.02 Mpa higher than the opening pressure of the pressure valve disc.

This hole is usually blocked by a bolt. After removing the bolt, you can install a pressure gauge here.

Both positive pressure valve disc and negative pressure valve disc can be sold separately.