Overfill Prevention Valve Model 71
The Model 71 overfill prevention valve provides a mechanical method of automatic fuel oil shut-off to prevent overfilling of underground storage tanks during a gravity filled delivery as required by NFPA 30 Flammable and Combustible Liquid Code. It is designed to satisfy EPA regulations covering overfill protection, “a device that will automatically shut off the flow of oil into the tank when the tank is no more than 95% full.”* It is recommended to be installed with a Preferred Fil-A-Larm system, which provides a pre-alert audible/visual
alarm and shut-off notification to the fill operator, prior to the actuation of the Model 71.
- Overview and specification
- Application
- Ordering Information
- Documents
Operation
The overfill prevention valve is a float-operated, two-stage
shut-off valve system. It is installed as an integral part of a
4" drop tube assembly. When the fuel oil level increases to
approximately 95% of tank capacity, the main valve closes.
A small bypass valve remains open to permit delivery hose
draining at a rate of approximately 2-5 GPM. If the oil level
reaches 98% of tank capacity, the bypass valve closes to
prevent accidental or intentional overfilling.
Please Note: On existing tanks, the drop tube may be
held in the tank coupling below the riser pipe. On these
installations, the existing drop tube must be removed to
accommodate valve operation.
Please Note: The overfill prevention valve is used with
“gravity fill” systems only, and is not intended for “pumped-in
fill” applications. It is for diesel or No. 2 fuel oil only.
Specifications
Valve Body: Cast aluminum
Float: Nitrile rubber, Closed cell foam
Valve: Aluminum
Seals: Viton
Upper and Lower Drop Tubes: Aluminum
The Model 71 is used for underground diesel or No. 2 fuel oil storage tanks where the tank is gravity filled (i.e. not applicable to “pumped-in fill” applications). The overfill prevention valve includes upper and lower drop tube sections. The upper section is flared, rests on the top of a 4" fill pipe, and is secured in place by the tight fill adaptor. The lower drop tube section extends into the tank and is cut off at either 6 inches from the tank bottom, or at the dimension required by local codes. The overfill prevention valve is installed between the drop tube sections. The valve can be installed from outside the tank without excavation (installation is as easy as changing drop tubes).
Preferred overfill prevention valve:
Model 71 for tanks buried to 5' of depth, with a maximum
inside tank diameter of 8'
Model 71-L for tanks buried to 9' of depth, with a maximum
inside tank diameter of 10'
Overfill Prevention Valve Model 71 Specification
Overfill Prevention Valve Model 71 Cutsheet
