Kromschröder VAH Flow Rate Regulator with Solenoid Valve

Kromschröder VAH is a flow rate regulator that keeps the gas flow in proportion to the air flow and also acts as a safety gas solenoid valve. This page covers the VAH code only. Sibling codes in the valVario series: VRH (same flow rate control but without a solenoid valve), VAD (spring-set constant pressure governor), VAG (1:1 pressure ratio) and VAV (variable pressure ratio 0.6:1–3:1). The VAH is distinguished by control from the air flow measured across an orifice (three connections) and the integrated solenoid valve.

Specifications

• Function: keeps a constant gas/air ratio on modulating-controlled and stage-controlled burners; the gas flow rate is controlled in proportion to the air flow rate. The integrated solenoid valve shuts off the gas or air supply safely. The valve is closed when power is off.
• Differential air pressure Δpsa (psa – psa-) and differential gas pressure Δpd (pd – pd-): each 0.6–50 mbar; gas:air ratio 1:1; zero point N adjustable at low fire ±5 mbar.
• Max. inlet pressure 500 mbar (ANSI/CSA version 350 mbar), always higher than Δpsa + max. gas pressure at the burner + pressure loss + 5 mbar. In the horizontal position with modulating control: min. inlet pressure 80 mbar.
• The differential air pressure is measured with a measuring orifice in the air line (straight inlet and outlet sections ≥ 5 DN) connected to psa and psa-; there is also a pd- connection. Connection: 3 x 1/8″ compression fittings for 6 x 1 tube (VAH..E) or NPT (VAH..A).
• Sizes 1–3: VAH 115, 120, 125, 240, 350 (DN 15, 20, 25, 40, 50), Rp or NPT thread; ISO 7005/ANSI flange on 240 and 350. Voltage 230, 200, 120, 100 V AC or 24 V DC; coil 25 W (size 1), 36–40 W (sizes 2, 3).
• Aluminium housing, NBR seal; -20 to +60°C; IP 65.

Dimensions and weight (Rp thread version)

The NPT version (NPT thread, ANSI flange) has its own dimension table in the document (section 9.2). ISO flanges exist on sizes 240 and 350 only.

Difference from VAD, VAG, VAV, VRH

• Versus VRH: the VAH has an integrated solenoid valve (safe shut-off of gas or air, needs a power supply); the VRH has no solenoid valve, so it does not close the gas itself.
• Versus VAG and VAV: the VAH regulates gas flow rate from the air flow measured across an orifice, whereas VAG/VAV regulate gas pressure from an air control pressure.
• Versus VAD: the VAH does not hold a fixed spring-set outlet pressure.
• Dimensions: the VAH body is taller than the same-size VAx (H2 = 100 mm versus 82 mm on size 115) and slightly heavier (VAH 115: 2 kg, VAD/VAG/VAV 115: 1.8 kg).

Applications

The valVario series is used in gas control and safety systems in the iron, steel, glass and ceramics industries, and in residential or commercial heat generation such as the packaging, paper and food industries. The VAH keeps a constant gas/air ratio on modulating-controlled and stage-controlled burners and shuts off the gas or air supply safely.

Standards / Certification

• Class A control to EN 88-1:2011+A1:2016; Class A, Group 2 safety valve to EN 13611 and EN 161:2011+A3:2013; EN 126:2012; EN 1854:2010 (declaration of conformity for VAD/VAG/VAV/VAH/VRH sizes 1–3). UKCA: BS EN 88-1, EN 126, EN 161. Meets the technical specifications of the Eurasian Customs Union.
• Suitable for systems up to SIL 3 / PL e: single channel up to SIL 2 / PL d; SIL 3 / PL e with two redundant devices.

Compatibility / Installation

• Fit a measuring orifice (VMO) in the air line downstream of the air control valve, with straight inlet and outlet sections ≥ 5 DN; a fine-adjusting valve VMV can be used in the gas line.
• Do not install a gas solenoid valve VAS between the VAH and the fine-adjusting valve VMV; the VAS could no longer act as a second safety valve there.
• Black solenoid actuator vertical or tilted up to horizontal, not upside down; install a filter upstream.

What to send for a quote

To quote quickly and against the right code, please send:

• full type code (for example VAH with size 1-3 / DN, Rp or NPT thread or ISO flange)
• air flow rate/differential pressure across the measuring orifice and the gas pressure at the burner
• air control connection type (E or A), coil voltage (230, 200, 120, 100 V AC or 24 V DC)
• gas type (natural gas, gaseous LPG, biogas, hydrogen or clean air), inlet pressure and required flow rate
• quantity

CAD replies with a quote within 24 working hours.

Technical documentation (datasheet)

Kromschröder: Technical Information VAD, VAG, VAH, VAV, VRH, VCD, VCG, VCV, VCH (English, edition 08.23). This is the manufacturer’s single document for the whole series; the data for VAH is in the matching sections.