The Flow Control Group design, manufacture and install a complete range of Decanting Arms for a wide range of applications in the water, wastewater, and industrial process sectors.

The specification and selection of a Decanting Arm and its operating protocols is essential to its optimum performance.

The Flow Control Group are one of Europe’s leading manufacturers of specialist flow control equipment.

We design, manufacture and install a range of products including penstocks, flap valves, stop logs, floating arms, hydrostatic valves and specialist knife gate valves.

The Group also design and manufacture a complete range of operating equipment including valve mounting kits, extension spindles, pedestals, locking devices, chainwheels and handwheels.

Decanting Arms are used to provide a method of controlling the rate of discharge of waste liquors of all kinds, prior to their entry into Drains and/or Treatment Plants,

Decanting Arms are incorporated into Balancing Tanks or Settling Tanks. To operate the arm is arranged such that the head remains constant over the full depth of drawdown ensuring a substantially constant rate of discharge between top and bottom liquid levels.


Body, bridge, bellmouth and gland shall be frame manufactured from welded rigid mild steel sections to mild steel grade 43A BSEN 10025:S275 JOH 1997/J2H 1994, stainless steel grade 304/316 BSEN10088-2 (1.4301/1.4307-1.4401/1.4404) and shall have removable stainless steel 304/316 BSEN10088-2 (1.4301/1.4307-1.4401/1.4404), cast iron BSEN 1561:2011 grade 250 min.

The bend will incorporate a sole plate and integral guides and adjustable stainless steel trunion pin. The flange shall be designed so that a chute can be fitted. The outlet flange will be drilled to suit a mating flange.

The sole plate will be suitable for grouting and bolting to a horizontal surface.

The swivel bend will have bonded and pinned cast copper rings to BSEN 1982:2008. The gunmetal will be machined to the non-acceptance of 0.0025” (0.06mm)

For the floating arrangement the chute shall be manufactured from stainless steel grade 304/316 BSEN10088-2 (1.4301/1.4307-1.4401/1.4404). Fitted at the top of the chute should be either single or twin floats. Around the float there should be a scum box. If required and to control the flow a suitably sized orifice plate shall be fitted to ensure a constant flow discharge. To prevent siphoning during operation breather pipes should be included at the top of the chute.


For the decanting arrangement the chute shall be manufactured from stainless steel grade 304/316 BSEN10088-2 (1.4301/1.4307-1.4401/1.4404). Fitted directly to the top of the chute should be a stainless steel grade 304/316 BSEN10088-2 (1.4301/1.4307-1.4401/1.4404) guide rod. The guide rod shall be fitted to a stainless steel grade 304/316 BSEN10088-2 (1.4301/1.4307-1.4401/1.4404)  min trunnion shaft. 

Operation should be through a trunnion mounted drive sleeve. The Decanting valve operating stem will be of the rising type and be manufactured from stainless steel grade 304/316 BSEN10088-2 (1.4301/1.4307-1.4401/1.4404)  min. The stem will work through a machine cut trunnion operating drive sleeve housed in a pillar.

Headstocks shall be manufactured from heavy gauge mild steel and shall be heavy duty galvanised to BS729 after blast cleaning.

The Decanting valve will be clockwise closing at the hand wheel. This will be clearly marked on the hand wheel (integrally or mechanically fixed. the hand wheel will be no smaller than 300mm and geared that one operator can operate the valve using an effort of approximately 180N.

Installation of the Penstocks will be by electro zinc plated mild steel BS 7371-8:2011 or stainless steel grade 304/316 BSEN10088-2 (1.4301/1.4307-1.4401/1.4404) expanding or resin anchors.

Following installation final adjustment and initial lubrication is to be undertaken and the door operated through one cycle (or as recommended by the manufacturer). If considered necessary by the client’s representative a leakage test shall be undertaken at the maximum specified head.

Mild steel -Cast Iron parts will be coated in-accordance with the following

Galvanise to BS729 and or ‘T’ wash

Two pack epoxy 150 microns DFT. – black.

Stainless steel self colour, the stainless steel should be cleaned after fabrication by approved methods




    Unit 1 Mount Street Business Park
    Mount Street Nechells
    West Midlands
    B7 5QU

    Tel: 0121 752 8870

    Oil and Gas Division

    Cooper Drive
    Springwood Industrial Estate
    Braintree Essex
    CM7 2RF

    Tel: 01376 321211

    Industrial Process Division

    Cambridge Mills Cambridge
    Nr Dursley
    GL 2 7AA

    Tel: 01453 826612