Frequently Asked Questions

The Oil Stop Valve (OSV) is designed for easy, efficient operation in confining oil spills to the premises. It is used in oil manholes to prevent the entry of oil into the environment following a spill. It is also used in oil/water gravity differential separators and coalescing type separators preventing oil intrusion into the effluent. The valve operates on a buoyancy principle. The ballasted float, the only moving part, is weighted for a specified gravity of 0.95. In the water, the float will float and keep the valve open.

For the valve to operate properly at the required flow(s), the valve discharge pipe center should be below the liquid level at a distance equal to (or greater than) the associated head loss or the reduction in the fluid as it moves through a pipeline. To prevent premature valve closure due to leakage a 4’ diameter catch basin for the Oil Stop Valve 4" & 6", and a 5’ diameter for the OSV 8", OSV 10" and OSV"12. EXCEEDING THESE FLOW RATES MAY CAUSE PREMATURE CLOSING.

4" Diameter       160 GPM

6" Diameter       360 GPM

8" Diameter       600 GPM

10" Diameter       900 GPM

12" Diameter      1400 GPM


All valves with plain end connections are supplied with a Fernco rubber coupling and two stainless steel worm drive hose clamps. Slide the coupling on valve discharge and install the clamps by sliding them on the coupling. On flanged end connections line up the flange bolt holes, insert a gasket and bolt flanges. Do not tighten bolts at this time. Flanges should be flat faced and of the same design.


Line up the valve discharge with the outlet pipe, leave 1/4" gap between pipe ends, and slide the coupling and clamp on the outlet pipe.

The original Spill Prevention, Control, and Countermeasure (SPCC) rules were published on Dec. 11, 1973. Final SPCC amendments were published in 2002. is The regulations apply to 'small facilities' and 'oil filled equipment'. To comply with the regulations a company should conduct an engineering assesment to determine the potential for oil discharge and the resulting impact.

PVC construction is economical and a good choice for warm climates. Stainless steel is the alternative if fire is possible. There is no connection inside the sump to burn and fail. Stainless is also used in colder climates to eliminate an electric freeze protection package.

No, there is only one moving part. It operates without power. A visual check is required once per year.