Type 55 water safety shut-off valve – DN 25/50, PS 16/100
Closes in the event of an impermissible rise in pressure in the heating water circuit and protects the boiler of a gas preheating system.
Automatic shut-off
Closes completely in the event of both a gradual and a sudden rise in pressure.
Type 55 Water Safety Shut-off Valve for heating water circuits in gas preheating systems
The Type 55 water safety shut-off valve protects the boiler in a gas preheating system against excessively high pressure. If a leak occurs in the tube bundle of the gas-liquid heat exchanger, gas can enter the heating water circuit. If the pressure exceeds the set point, the valve closes completely and isolates the boiler from the heat exchanger side.
If the pressure drops below the set point again, the spring reopens the valve. The Type 55 is designed for heating water and for installation in gas preheating systems in accordance with DVGW Worksheet G 499.
The EU type examination certificate specifies versions in DN 25 and DN 50, for PS 16 or PS 100, and a temperature range of 0 to +60 °C. Installation is possible horizontally or vertically; optionally, an inductive sensor can indicate the valve position.
PS 16 or PS 100
Specified pressure ratings for Type 55.
DN 25 and DN 50
Certified nominal diameters for Type 55.
EN and ASME connections
EN 1092-1 and ASME B16.5.
No ignition sources
Electrical accessories comply with ATEX requirements – low risk.
Optional inductive sensors
Indicates the valve position.
Tested design
PED 2014/68/EU; DIN EN 14382 where applicable.
Advantages and versions of the Water SAV Type 55
Closes regardless of pressure trends
Automatic return to the open position
Installation and monitoring according to the system
Technical specifications of the Type 55 water safety shut-off valve
An overview of the key specifications for the Type 55 – from the medium, nominal diameters and pressure ratings to temperature, connections and materials.
Scope of delivery
- Connecting bolts depending on flange
- 2 × seals
Design and operation of the Type 55 water safety shut-off valve
The Type 55 water safety shut-off valve operates automatically through the interaction of the prevailing pressure and the set spring force. If the pressure in the heating water circuit exceeds the set point, the valve completely shuts off the flow. Once the pressure has been relieved, it reopens automatically; optionally, the valve position can be detected via an inductive sensor.
Spring, valve and stainless steel housing
The Wasser SAV Type 55 operates with a compression spring that keeps the valve open during normal operation. The cut-off pressure is set via the adjustment mechanism within the specific operating range of the spring used. The housing is made of 1.4541 stainless steel; EPDM is specified as the sealing material.
A sensor rod transmits the valve movement to the optional inductive sensor. This indicates whether the valve is open or closed. The sensor is factory-set and must not be readjusted. The G 1/4 vent on the side must remain unobstructed during installation.
Eine Sensorstange überträgt die Ventilbewegung auf den optionalen induktiven Sensor. Dieser zeigt an, ob das Ventil geöffnet oder geschlossen ist. Der Sensor wird werkseitig eingestellt und darf nicht nachjustiert werden. Die seitliche Beatmungsöffnung G 1/4 muss beim Einbau frei bleiben.
How the Type 55 works
In normal operation, the spring keeps the valve open. If the pressure in the heating water circuit rises above the set point, the pressure force overcomes the spring force. The valve moves in the closing direction until the seal is pressed upwards against the housing and the flow is completely shut off. This operating principle applies to both slow and sudden pressure rises.
If the pressure drops below the set point again, the spring reopens the valve. The directional arrow on the unit indicates the heat exchanger side. The shut-off pressure must only be adjusted by qualified personnel, taking into account the specific spring range.
Technical Specification and Enquiry regarding the Water-SAV Type 55
Factors relevant to selecting the appropriate model include, amongst others, the maximum permissible gas inlet pressure, the operating pressure and temperature of the heating water, the desired cut-off pressure, the nominal diameter, as well as the flange standard and pressure class. Please also specify the installation position and the required sensor size.