Vertical safety group assembly for hot water storage heaters

Item number: 140

Safety valves are the last devices to protect pressure equipments and people working on them. For this reason safety valves have to be well manufactured, assembled and periodically checked.

Their design and construction are on our own responsibility, but the choice of their correct size and type depends on the decisions of the manufacturer of the equipment where the valve is fitted. Maintenance is on final user’s responsibility to whom we are giving, hereby, all necessary instructions and information.

Technical specifications

A 84,5
B 100
CH 30
DN 3/4"
PZ. 1/12
kg 5
CALIB. 7 bar

Observation on European Normative UNI EN 1487

It is specified that normative UNI EN 1487 define sizes, materials and requested performances (including test methods) of hydraulic safety groups for nominal dimensions from DN15 to DN40 and working pressure from 1 bar (0,10 MPa) to 7 bar (0,70 MPa). Hydraulic safety groups are to be connect to water heaters and tanks through the fitting of cold-water inlet source, with a temperature of distribution of 110° for all energy sources. Furthermore, they control and limit a pressure inside water heaters and forbid, having this function, reflux of the hot water into water system and contamination of the water inside heaters by drain water.

Hydraulic safety groups are not controlling temperature, but can control hydraulic safety of water heaters if mechanic resistance of heater remain at least equal to nominal pressure capacity.
So, it can be state that operators simply have to request and install safety groups in accordance with European Normative UNI EN 1487 by disposition of Ministry of Industry n°829571 from 26th March 2003.

P.S. “Ball-valve” type.

Technical characteristics

  • Body: brass UNI EN 12165 CW617N chrome-plated
  • Plugs and caps: PA6
  • Diaphragm: EPDM 70SH
  • Springs: steel UNI 3823
  • Control knob: ABS
  • Check valve: CLASS A
  • Maximum working pressure: 10 bar (1 MPa)
  • Maximum working temperature: 120 °C
  • Safety relief valve pressure setting: 7 bar (0,7 MPa) ±0,1 bar (0,01 MPa)
  • Maximum output of the water heater: size 3/4” 10 kW
  • Discharge flow rate at 8,5 bar (+20% PS): with water: > 600 l/h. with steam: > 220 kg/h
  • Can be used with siphon art. 145 adjustable


The safety group assembly “UNIVAL” can be installed on elettrical and gas water heaters which have a power till 10 Kw (3/4″ connection). More over this device protects water heater from internal over pressures, allowing the passage of water from the inlet source to the water heater when the pressure inside water heater diminish for 0,1 – 0,2 bar (0,01-0,02 MPa). It also prevent that water returns in the supply piping (antipollution). The safety unit is set by means of compression of a spring to a standard opening value of 7 bar (0.70 MPa). During testing the set rate is gauged on the second opening of the safety mechanism. During discharge the device becomes watertight again when the pressure decreased for 1 bar (0,01 MPa) comparing to the opening valve tollerance set rate ±1 bar (0,10 MPa).

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