API · ASME · DIN · EN standard industrial valves
Variable Orifice Double Regulating Valves
Variable orifice double regulating valves balance on the valve's own variable restriction rather than a fixed orifice, in the larger flanged sizes where a separate flow-measurement device would otherwise be needed in the line. The range is read from the manufacturer's flow measurement graphs rather than an integral orifice. Selection turns on the flange class against the American-standard pipework, the DN65-DN300 band, and how the commissioning crew reads flow — graphs against a separate fixed-orifice or measurement device. The typical build carries a regulating disc, double regulating device and position indicator, and the common commissioning variant adds a pair of test points so flow is measured and regulated on the valve itself; where higher measurement accuracy is needed the DRV is coupled with a fixed-orifice metering station as a commissioning set. Flow sizing runs through the manufacturer KV chart (KV = Q x 36 / sqrt(hl), headloss in kPa), with Kv values published per opening percentage from 100% to 20% open - DN65 falls from Kv 78.5 fully open to 10.5 at 20% open.
Part of the Balancing Valves family
Last updated: 2026-10
Family specifications
| model line | DA931 DN65 to DN300 Variable Orifice Double Regulating Valve (VODRV) – Ductile Iron Class 125 |
|---|---|
| size range | DN65 to DN300 |
| body materials | Ductile Iron |
| end connections | Flanged connections - ANSI Class 125 |
| flow measurement | Per the DOC SD1-20 Flow Factor KV & KVs Chart: KV = Q x 36 / sqrt(hl) with published Kv values per opening percentage (DN65-300); see Flow Measurement Graphs for the benchmark DA931 line. |
| pressure class | PN25 |
| operation | Manual (handwheel) |
| test points option | Available fitted with test points for variable-orifice flow measurement and regulation — the standard configuration for commissioning set-ups. |
| construction | Fitted with a regulating disc, double regulating disc, double regulating device and position indicator. |
| commissioning set pairing | Can be coupled with a fixed-orifice metering station as a commissioning set: the DRV regulates, the fixed orifice measures. |
| max temperature note | Cast-iron double regulating variants carry a restricted-use maximum temperature of 180 degC. |
| flange standard variant | PN16 variant to BS EN 1092-2 exists alongside the PN25/Class 125 benchmark segment. |
| kv sizing formula | To size within a suitable hl band: KV = Q x 36 / sqrt(hl). To find hl with known KV: hl = Q2 x 1296 / KV2. To find flow with known KV: Q = sqrt(hl x KV) / 36. Where Q = Flow l/s and hl = headloss in kPa. |
| kv by opening table | Kv values are published per opening percentage for the BV203/BV307 double regulating range, DN15 to DN300 from 100% down to 20% open; e.g. BV203 DN65: 78.5 (100%), 65.8 (90%), 53.5 (80%), 45.3 (70%), 37.1 (60%), 29.6 (50%), 21.6 (40%), 14.1 (30%), 10.5 (20%); DN300: 2430 down to 644. |
| fvo design | Variable orifice single unit Y-pattern globe valves, Fitted with a pair of measuring plugs, Microset handwheel and presetting scale is readable from all directions, Regulating and isolating functions, Setting can be locked with allen key |
| fvo end connections | BS 4504 PN16 / EN 1092-2 PN16 / BS 4504 PN25 / EN 1092-2 PN25 / ANSI Class 150 (Specify on order) |
| fvo design standard | BS 7350 |
| fvo application | Applicable for hydronic balancing of heating and cooling systems |
| fvo working pressure | 16bar, 25bar |
| fvo shell test pressure | 24bar, 37.5bar |
| fvo seat test pressure | 17.6bar, 27.5bar |
| fvo working temperature | -10°C ... 120°C |
| fvo suitable media | Water |
| fvo model variants | F63V16, F63V25 |
| fvo body material | Ductile Iron |
| fvo bonnet material | Ductile Iron |
| fvo stem material | Stainless Steel 410 (DN65 ... DN300), Stainless Steel 431 (DN350 ... DN600) |
| fvo balancing cone material | EPDM coated DI |
| fvo gland material | Brass (DN65 ... DN150), Ductile Iron (DN200 ... DN600) |
| fvo handwheel material | DZR Brass |
| fvo packing material | Non-Asbestos |
| avo design | variable orifice double regulating valve (VODRV) |
| avo body material | ductile iron |
| avo sealing cone material | EPDM sealing cone |
| avo shutoff class | tight shut off |
| avo end connection | Flanged ends are drilled to PN16 |
| avo position indicator | a visual position indicator on the handwheel |
| avo test points | 2 fitted test point and extensions |
| avo pressure rating | 16 bar |
| avo working temperature | -10°C to +120°C |
| avo size options | 2" (DN50), 2.1/2" (DN65), 3" (DN80), 4" (DN100), 5" (DN125), 6" (DN150), 8" (DN200) |
| vvo typology | Static balancing |
| vvo body material | Cast Iron |
| vvo design | Variable orifice cast iron double regulating valve |
| vvo size range | Diameters from DN040 – 11⁄2” to DN400 – 16′′ |
| vvo flange standard | Flanged PN16 according to EN1092-2 (ex DIN2533) |
| vvo face to face standard | Lengths according to EN558-1 series 1 (ex DIN3202 F1) |
| vvo coating | Alkyd/acrylic single layer waterpaint coating (50-100μm) |
| vvo kv tolerance | Tolerance on nominal Kv for completely open valve ±5% |
| vvo test points | With plugged threaded drains (1⁄4” ISO 7/1Rp) for test points, Provided with test points (given unmounted) |
| vvo certification | TR CU 010 compliant, Free of CE marking for DN≤300 (cat. according to Art. 4.3 Dir. 2014/68/EU) |
| vvo pressure rating | PN16 |
| vvo size options | DN 40 , 50 , 65 , 80 , 100 , 125 , 150 , 200 , 250 , 300 , 350 , 400 |
| vvo working conditions | water, -10°C to +110°C below 0°C only for water with added antifreeze fluids over 100°C only for water with added anti-boiling fluids (ethylene glycol or propylene glycol mixtures up to 50% may be used) |
| vvo media restrictions | Not suitable for: gases group 1 & 2, liquids group 1 (Dir. 2014/68/EU) |
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
Supply terms, order quantities and lead time are agreed per order — state the destination country and required schedule with the inquiry.
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 sizes and pressure ratings are available for variable orifice double regulating valves?
The published size range is DN65 to DN300, and the published pressure ratings are PN25. Availability of a specific size and rating is confirmed at quotation.
What materials are variable orifice double regulating valves available in?
The published specification lists body materials: Ductile Iron. Material availability for a specific size and rating is confirmed at quotation.
What end connections do variable orifice double regulating valves support?
The published specification lists Flanged connections - ANSI Class 125 as the available end connections. The connection for a specific size is confirmed at quotation.
What should a quotation inquiry for variable orifice 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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