Batescrew manufacture non-return valves in two configurations, either fully enclosed in-line valves, as illustrated above right, or as simple end-of-line flaps.
Simple flap type valves have various arrangements for flange, welded or grouted installation.  All Batescrew n-r valves have stainless steel seats and rubber seals.  The type of rubber compound used is chosen to suit the intended operating head, which must be indicated when ordering.
Maximum operating head is eight metres for standard valves, higher head versions are made to order.

Corrosion Resistance.  Normal construction is of mild steel, hot dip galvanised.  Stainless Steel, in grades 304L or 316L, may also be specified.

Sealing is between a stainless steel seat, welded to a pipe spigot which forms part of the valve body, and a resilient disc clamped to the pivoting flap. The flap has dual pivot points for reliable seating.
The stainless seat is inclined at an angle of five degrees from the vertical, to provide gravity-assisted sealing when the pressure head is low, and to ensure full closure at nil pressure, thus barring entry to insects and vermin.
The main pivot pin is stainless steel, supported in bronze bearings and grease lubricated via a nipple on exposed flap valves, water lubricated on in-line valves.

Applications.  Common applications include:
    Pumping system protection against reverse flow.
    Automatic control of multiple drainage lines into a common pumping sump.
    Prevention of back-flow at drainage outfalls into streams and tidal estuaries.
The Batescrew Technical Services Dept. will assist in adapting standard products to meet unusual needs.  Please contact our office regarding features not listed here, eg. retarded closing rate, moment reduction or balancing, remote actuation, head loss calculations etc.

Pressure Surge Protection.  When in-line non-return valves are used it may be necessary to guard against pressure surges.
Details of the types of protection commonly used, are given in the section In-Line Valves.