Balancing Valves Β· Double Regulating Valves
Bronze Double Regulating Valve PN25
A bronze double regulating valve balances a hydronic circuit in two steps: the handwheel sets a precise opening for design flow and a memory stop locks that position, so the valve can be closed for isolation and reopened exactly to its balanced setting. The benchmark execution is a PN25 bronze body valve with threaded female-female ends, WRAS approval for potable water contact, and handwheel operation sized for circuit-level double-regulating work in heating and chilled water systems.
Part of the Double Regulating Valves family
Last updated: 2026-11
Specifications
| weight | 0.5562kg |
|---|---|
| product finish | Bronze |
| size mm | 20 |
| valve type | Double Regulating Valve |
| model designation | D921 |
| size range | DN15 to DN50 |
| pressure class | PN25 |
| temperature range | 10 - 120Β°C |
| end connections | Sizes 1" to 2" taper threaded, Sizes 1/2" & 3/4" DN15 & DN20 parallel threaded |
| thread standards | BS EN 10226-2 (ISO 7-1) formerly BS 21, BS EN ISO 228-1(formerly BS 2779) |
| measurement accuracy | accuracy of +/-5% on all settings |
| orifice design | integral fixed oriface design |
| body materials | Bronze |
| adaptor kits | Adaptor kits for use with copper tube also available |
| ansi thread option | Also available threaded to ANSI B1.20.1. Please add suffix AT to denote American Thread i.e. D921AT/D923AT |
Application & selection guidance
Select this execution as the circuit-level static balancing and isolation point on heating, chilled water and potable-acceptable systems inside the PN25 envelope, wherever commissioning must set design flow once and later isolation must not lose that setting. Pair it with a flow measurement device at metering points, and size the valve so the balancing duty sits in the upper part of the handwheel travel for resolution and repeatability.
Frequently asked questions
What makes a double regulating valve different from a plain balancing valve?
The double regulating function couples the throttle to a memory stop: once the handwheel is set to design flow and locked, the valve can be fully closed for isolation and reopened to exactly the same setting. A plain throttle valve loses its setting at every closure, so recommissioning starts from zero.
Which materials, size and rating does this execution cover?
The benchmark product page lists a bronze body and finish, PN25 pressure rating, female-female threaded ends, a 20 mm size execution weighing about 0.5562 kg, handwheel operation, and WRAS approval supporting potable water contact.
What information is needed to quote a double regulating valve?
Line size and end connection (threaded or flanged per the circuit), design flow rate and the target pressure drop for balancing, system pressure class against PN25, medium and temperature against the bronze body, and any potable water requirement covered by the approval.
Ordering & documentation
Documents
Ask for the documentation set you need with the inquiry β typical items for this execution (material certificates, test reports to the listed inspection standard, dimensional drawings) are confirmed and supplied with the quotation.
Quotation
A quotation-ready inquiry states: nominal size and pressure rating, body and seat material preference, end connection, operation, and the service medium with temperature. Typical values on this page are benchmark reference ranges; the binding values are confirmed at quotation.
Sample & supply
Supply terms, order quantities and lead time are agreed per order β state the destination country and required schedule with the inquiry.
Storage & shipping
Store valves with seats and seals protected from UV, ozone and deformation, keep end-face protectors on until installation, and for elastomer- or PTFE-seated executions avoid prolonged outdoor storage β seat compounds age fastest in direct sunlight and freezing conditions.
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