A Floor Type Pressure Relief Valves are for placing in the bottom of tanks to keep empty tanks from floating when there is an excess of ground water underneath and around them. When this condition exists, the outside water pressure will raise the cover of the valve and allow the water to enter the tank and equalize pressures inside and outside of the tank, preventing the tank from floating.
The Wall Type Pressure Relief Valve is for side wall installation in tanks and digesters. The valve has a 4" or 6" flanged end for connection to a flanged wall pipe. Iron body, bronze mounted, it is equipped with a soft, composition rubber seat, so that if particles of grit lodge on it, the head of liquid in the tank will still force the flap closed tightly, and prevent seepage of liquid out into the ground. The seating material has been chosen for its resistance to deteriorating effect of the sewage.