API · ASME · DIN · EN standard industrial valves
Double Regulating Valves
Double regulating valves are static balancing valves with a calibrated handwheel and positive stop: the setting can be preset, locked and reopened to exactly the same position, which is what hydronic commissioning requires. The range covers a bronze PN25 line in DN15 to DN50 (including a DN15 low-flow variant) and a ductile iron PN16 line in DN65 to DN600, with gearbox-operated (DN50-DN600) and lever-operated (DN65-DN150) variants and flanged or BS EN 10226 taper/parallel threaded end connections. Selection turns on line size and flow, bronze versus ductile iron against the system, handwheel operation at the installed position, and the memory-stop setting range. Multi-source references add the operating frame: the UK-coined double-regulating term means a set position retrievable exactly after closing via a memory stop, primary duty of creating flow resistance in the bypass of 3-port mixing/diverter valves, Y-pattern globe bodies presenting the smallest pressure loss when fully open, VODRV Kv-versus-delta-P setting methods with plus-or-minus 15% accuracy near the minimum set point, FODRV commissioning valves with fixed-Kvs orifice or venturi measurement at typically +5% accuracy, venturi pressure recovery for low-differential systems, unidirectional installation respecting the body flow arrow, DRV bypasses simulating future system load, and the variable-flow trend replacing commissioning valves with PICVs.
Part of the Balancing Valves family
Last updated: 2026-11
Family specifications
| bronze line | D921 DN15 to DN50 Double Regulating Valve (DRV) – Bronze PN25 |
|---|---|
| bronze low flow variant | D923 DN15 Low Flow Double Regulating Valve (DRV) |
| ductile line | DM921 DN65 to DN300 Double Regulating Valve (DRV) – Ductile Iron PN16 |
| operation | DM925G / DM925L DN50 to DN600 1/4 Turn Gearbox Operated Double Regulating Valve (DRV) – Ductile Iron PN16 |
| operation | DM925LW DN65 to DN150 Lever Operated Double Regulating Valve (DRV) – Ductile Iron PN16 |
| end connections | End Connections Flanged |
| end connections | Sizes 1" to 2" taper threaded to BS EN 10226-2 (ISO 7-1) formerly BS 21 |
| body materials | Bronze, Ductile Iron |
| memory stop principle | a valve capable of being set to a desired degree of opening, locking that position with a memory stop to ensure the position can be retrieved exactly after the valve has been closed. |
| bypass duty 3port | In the UK the Double Regulating Valve [DRV] is primarily used to create flow resistance or a pressure drop in the by-pass of a 3-Port mixing or diverter valve or for simulating a load for a future loop. |
| no flow measurement | Keep in mind that this balancing valve doesn’t provide any flow measurement. |
| butterfly memory stop ref | For line sizes from DN 65, Butterfly valves that have been fitted with a memory stop can offer the same functionality as the traditional globe design while being lighter, smaller, easier to install and less costly. |
| vodrv definition | The DRV is sometimes referred to as “ Variable Orifice Double Regulating Valve ” [VODRV]. |
| vodrv kv method | The flow rate is calculated using the Kv value for each handwheel setting and the Δ P across the valve. |
| vodrv accuracy ref | The measurement accuracy may be adversely affected by this principle by plus or minus 15%, when close to the minimum set point (25% open as per CIBSE guideline). |
| vodrv unidirectional | The valve is unidirectional and the direction of the flow arrow on the valve body must be respected. |
| fodrv definition | The Fixed Orifice Double Regulating Valve [FODRV] is also referred to as Commissioning Valve or Commissioning Valve Set. |
| fodrv accuracy ref | The accuracy of this type of valve is typically + 5%, depending on the opening position. |
| venturi pressure recovery | The FODRV with venturi minimises turbulence and recovers a significant proportion of the pressure loss after flow has passed through it, and can be close coupled, which makes the venturi FODRV suitable for systems with low differential pressure. |
| picv variable flow trend | Commissioning Valves are not suitable for variable flow and have been replaced by PICVs. |
| bypass future load | Install a DRV bypass between flow and return to simulate future system load. |
| y pattern globe body | Typically this valve is a Y pattern globe valve arranged in this way to present the smallest pressure loss to the system when fully open. |
| double regulating meaning | The description DOUBLE regulating means that it has a feature whereby you can set the position that the valve is to operate at in such a way that you can still close the valve for maintenance purposes. |
| resistance reduces flow | Adjustment of this valve will add resistance to the system and hence reduce the flow. |
| peer fodrv line | Peer FODRV execution: fixed-orifice commissioning valve in corrosion-resistant brass with brass test points, screwed female BSP, PN25, -10°C to 120°C |
| peer vodrv line | Peer VODRV execution: variable-orifice double regulating valve in ductile iron, flanged PN16, -10°C to 120°C, supplied with 2 test points |
| dr1 venturi valve construction | Balancing valve for hydraulic systems. Flow meter with Venturi device. Stainless steel obturator. Complete with quick-fit pressure test ports. |
| dr1 body material | Material : dezincification resistant brass DR |
| dr1 temperature range | Medium temperature range : -20–120 °C |
| dr1 max working pressure | Maximum working pressure : 16 bar |
| dr1 glycol limit | Maximum percentage of glycol : 50 % |
| dr2 memory stop principle | Memory stop/Sealing locking The valves are equipped with an adjustment position memory system that, after full closure which can be necessary for various reasons, allows easy re-opening at the initial position. |
| dr2 setting seal locking | There are two holes on the knob that can be used to seal (5) the setting position to avoid or detect any tampering over time. |
| dr2 presetting method | Knowing the value of the pressure drop p that needs to be created by the valve with a certain flow rate G, you can obtain the adjustment position number for the knob (PRESETTING). |
| dr2 adjustment scale | clockwise turn of the knob moves the red indicator by one step, from position 0 (valve closed) to position 6 (fully open valve). In addition, the decimal graduations of the black micrometric scale enable further refining of the adjustment. |
| dr2 installation clearance | The balancing valves must be installed in such a way as to ensure free access to the pressure test ports, drain cocks and the adjustment knob. The valves can be fitted on either horizontal or vertical pipes. |
| dr3 fodrv definition | is a fixed orifice double regulating valve (FODRV) which uses a venturi to measure the flow of liquid passing through the valve. |
| dr3 venturi definition | A venturi is a fixed orifice device consisting of two different diameters with a tapered section between them. The smaller diameter is referred to as the throat. |
| dr3 venturi upstream | The venturi is located upstream of the double regulating valve which provides stable flow measurement during flow regulation. |
| dr3 body materials | Component Material Grade Body DZR alloy BS EN 12165 CW602N Cover DZR alloy BS EN 12165 CW511L Stem DZR alloy BS EN 12164 CW724R Regulating disc Stainless steel AISI 303 Seal seat DZR alloy BS EN 12165 CW602N Disc seal PTFE Seals EPDM rubber |
| dr3 memory stop restriction | The valves are equipped with an adjustable memory stop that, after full closure allows easy re-opening to the set position. |
| dr3 position indicator | The valve position is indicated by 2 digits on the upper side of the handwheel, one digit indicates the number of full turns from closed (6) and the second indicating the partial turn (10). |
| dr3 technical data | Number of adjustment turns: 6 Female connecting threads: BS EN 288-1 |
| dr3 stem seal design | The double `O' ring stem seal (3) prevents water coming into contact with the actuating thread of the stem and causing leakage. |
| dr4 threaded size range | Threaded version sizes DN 15 (1/2"), DN 20 (3/4"), DN 25 (1"), DN 32 (1 1/4"), DN 40 (1 1/2"), DN 50 (2") |
| dr4 flanged size range | Flanged version sizes DN 65, DN 80, DN 100, DN 125, DN 150, DN 200, DN 250, DN 300 |
| dr4 flange standard | DN 65, 80, 100, 125, 150, 200, 250, 300; PN 16 - EN 1092-2 |
| dr5 venturi valve role | Venturi valves provide balance, ease of commissioning, and shut-off in a wide range of HVAC systems. |
| disc materials | Ductile Iron, SS304, SS316, Bronze |
| shaft materials | SS410, SS431 |
| seat ring materials | EPDM, NBR |
| o ring materials | EPDM, NBR |
| bushing materials | PTFE, Bronze |
| size range | DN50 to DN150 |
| pressure class | Class 150, PN16 |
| design standards | DIN EN 13709, DIN 3356 |
| flanged end standard | EN 1092-1 PN25 |
| face to face standard | EN 558-1 |
| test standard | EN 12266-1 |
Scope & source notes
| measurement accuracy | Measurement accuracy: reference VODRV principle can drift plus or minus 15% near the minimum set point (25% open per CIBSE), while the tenant page presents a calibrated handwheel with no stated measurement accuracy - accuracy class is unstated on the tenant page. |
|---|---|
| line size alternative | Line-size alternative: reference practice offers butterfly valves with memory stops as functionally equivalent from DN 65 upward (lighter, smaller, cheaper), while the tenant globe-design DRV lines run DN65 to DN600 - the globe-versus-butterfly split is not represented on the tenant page. |
| system trend positioning | System-trend positioning: reference guidance states commissioning valves are not suitable for variable flow and have been replaced by PICVs, while the tenant page positions static balancing DRVs without the variable-flow caveat. |
| peer pressure material mix | Peer pressure/material mix: peer executions offer PN20 brass screwed FODRV lines and PN16 flanged ductile-iron VODRV lines, versus the tenant PN25 bronze and PN16 ductile-iron lines - peer brass PN20 sits between the tenant bronze PN25 and ductile PN16 bands. |
Ordering & documentation
Documents
Ask for the documentation set with the inquiry — typical items (material certificates, test reports to the listed inspection standard, dimensional drawings) are confirmed and supplied with the quotation.
Quotation
Send the medium, temperature, pressure, size and connection for a quotation-ready inquiry. Lead time, MOQ and price are confirmed at quotation, together with the documents to be supplied with the order.
Sample & supply
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Storage & shipping
Store valves with seats and seals protected from UV, ozone and deformation, and keep end-face protectors on until installation; storage limits and shipping arrangements for the selected materials are confirmed at quotation.
Frequently asked questions
What standards govern the design and testing of double regulating valves?
The published specification for this family lists DIN EN 13709, DIN 3356 as the design standards.
What sizes and pressure ratings are available for double regulating valves?
The published size range is DN50 to DN150, and the published pressure ratings are Class 150, PN16. Availability of a specific size and rating is confirmed at quotation.
What materials are double regulating valves available in?
The published specification lists body materials: Bronze, Ductile Iron. Material availability for a specific size and rating is confirmed at quotation.
What end connections do double regulating valves support?
The published specification lists End Connections Flanged as the available end connections. The connection for a specific size is confirmed at quotation.
What should a quotation inquiry for double regulating valves include?
The governing standard and class, nominal size, body and seat materials, the service medium with temperature, and the destination — anything missing is confirmed during quotation.
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