L. F. Manufacturing, Inc.

Doc.# IFS-1400 August 11, 1992

Under this item the contractor shall supply and install to the manufacturer’s recommendations a manhole – inflow protector – as specified hereafter. Rain Guard Model LFN-SV as fabricated by L.F. Manufacturing, Inc., Giddings, Texas or approved equal.

The manhole insert body shall be designed with six equally spaced re-enforcement ribs ( 1 1/2″ wide, 1/2″ deep, and 6 1/2″ long ) in the bottom and will support a minimum uniform load of 800 pounds. The insert body shall have a recessed area in the center of the bottom for protection of the valve body. The insert will have two nylon lifting straps designed to lift and support a minimum uniform load of 500 pounds. The completed manhole inflow protector and its associated valve body and components shall be manufactured from corrosion proof material suitable for atmospheres containing hydrogen sulfide and dilute sulfuric acid as well as other gases associated with wastewater collection systems.

Reinforcing Materials: The reinforcing materials shall be commercial Grade “E” type glass in the form of continuous roving, and chop roving, having a coupling agent that will provide a suitable bond between the glass reinforcement and the resin.

Interior Surfacing Material: The inner surface exposed to the chemical environment shall be a resin-rich layer of 0.010 to 0.020 inch thick. The inner surface layer exposed to the corrosive environment shall be followed with a minimum of two passes of chopped roving of minimum length 0.5 inch (13 mm) to maximum length of 2.0 inch (50.8 mm) and shall be applied uniformly to an equivalent weight of 3 oz/ft. Each pass of chopped roving shall be well-rolled prior to the application of additional reinforcement. The combined thickness of the inner surface and interior layer shall not be less than 0.10 inch (2.5 mm)

INSERT BODY: The insert body shall be fabricated from ACRYLONITRILE-BUTADIENE-STYRENE (ABS) high impact, high grade LS material specifications under ASTM D-256 method A, D-638, D-790, D-785, D-648 method A and D-635 as manufactured by Borg Warner Grade LS Cycolac or equal.

RELIEF VALVE: The gas relief valve shall be designed to relieve at a pressure of 1 psi and have a water leak down rate not to exceed 5 gallons per 24 hours. The valve shall be installed by means of a threaded hole tapped in the center of the insert body by the manufacturer.

INSERT GASKET: The gasket shall be made of closed cell neoprene and have a pressure sensitive adhesive on one side and be placed under the insert body rim by the manufacturer. The adhesive shall be compatible with the insert body material so as to form a long lasting bond in either wet or dry conditions of use.

LIFTING STRAP: The lifting strap material shall be polypropylene webbing 1″ wide, .100″ thick, 1100# tensile strength and shall be fastened to the insert body with stainless steel rivets and fender washers.