Valve FAQs

What do the abbreviations on the valve product pages stand for?

BS: British Standard

BSP: British standard pipe

CF: Copper alloy faced

DI: Ductile iron

DN: Nominal diameter

FBE: Fusion bonded epoxy

FF: Flat face

FLG: Flange

HW: Handwheel

ID: Internal diameter

LW: Lever weight

NRS: Non-rising stem

OS&Y: Outside screw & yoke

PCD: Pitch circle diameter

PFA: Allowable operating pressure

PN: Nominal pressure

RF: Raised face

SG: Spheroidal iron

SS: Stainless steel

STD: Standard

 

What is the best position for the valve?

We would always recommend a distance of five pipe diameters from any turbulence inducing component, such as an elbow, tee or pump.

What colour are T-T Flow valves?

Our valves are coated in a durable fusion bonded epoxy coating, the colour is RAL5005.

Which valve ranges are suitable accredited for potable water applications?

The following ranges are WRAS approved; Aquavault resilient seat gate valve (DN50 – DN300), Aquabrake air valve (1” – DN200) and swing check valve (DN50 – DN600).

Can a valve have a different flange drilling to its pressure rating?

Yes.  The pressure rating of the valve is cast into the body.  This is the maximum pressure the valve shell can withstand under working conditions.  However, the flange drillings could be PN6, PN10, PN16, PN25, PN40, ASA150, BS10 Table D, BS10 Table E or other.

Are there any design constraints?

Valves are designed for either clean/potable water or wastewater applications having a maximum media temperature of 70°C and maximum velocity of 3 m/s.  For valves outside of these parameters, please contact the sales office.

Can safety guards be fitted to either side of a swing check valve?

Yes.  Basic hand tools will be required.  Always relieve pipeline pressure and isolate the flow before commencing any work.

Does T-T Flow test every valve?

Each individual valve is subjected to a hydrostatic pressure test as it leaves the production line.  The body/shell is tested to 1.5 x PN and seat to 1.1 x PN.

What is an interlock? 

A valve interlock is a mechanical lock that can be used to authorise the operation of a sequence of valves.  For example, a valve can be operated by inserting the control key to the first lock which once operated, releases the second key to operate the second, and so on.  Contact the sales team to discuss your requirements on +44 (0) 1630 647200.

Are valve operating elements interchangeable? 

A valve operating element is the mechanism in which torque is transferred to the valve, normally a handwheel, stem cap (also known as a dolly or false cap) or lever.  These items are interchangeable across the T-T Flow range but may not necessarily fit valves from other manufacturers

How can I remotely operate my valve? 

Operating equipment is fabricated in-house to site-specific requirements in a variety of materials.  Extension spindles are available as a one-piece or sectional for site adjustment, also optional gaitored universal-joints to accommodate off-sets.  Headstocks, also known as pedestals, are fabricated in complementing materials and can be either thrust or non-thrust taking with the optional indication.  These are supplied fitted with various operating elements such as a handwheel, gearbox, actuator or interlock. Contact us to discuss your requirements.

Can a gate valve be used to throttle or regulate the flow? 

Wedge gate valves are designed for isolation duty, that is to say left in either the fully open or closed positions.  Using a gate valve to throttle (or regulate) the follow is likely to cause damage to the seats and/or wedge.  Other valve types are more suited to flow regulating or throttling.

Can gate valves be installed at end of line? 

Gate valves are not designed for end of line duty.  We also recommend the use of a suitability rated blanking flange for such applications.

Do you have any other questions? Please contact us on +44 (0)1630 647200 to speak to a member of T-T flow.