4
MS-MOI-IT-W-ML-07-19-Rev0
K0098S – Rev. A 02/2019
Watts Water Technologies, Inc.
UK
Technical Specifications
Connection:
threaded UNI EN 10226-1
Maximum inlet pressure:
2 bar
Ambient temperature:
-10÷60°C
Response pressure:
red spring 30÷130 mbar
blue spring 80÷600 mbar
Fuel:
all three families of gas (city gas, methane, LPG);
non-aggressive gases.
Material:
aluminium valve’s body and cover; stainless steel
springs; steel control piston; NBR rubber gasket and O-ring;
other parts made of brass, aluminium and galvanised steel.
General information
The relief valves in the
MS
Series
are normally closed.
The valves open solely is the inlet pressure is greater than the
calibration value. The valves close automatically when the pres-
sure returns to below the calibration value.
Installation
The relief valves in the
MS Series
conform to Directive
2014/34/EU (ATEX) in group II category 2G and in group II cat-
egory 2D; as such they are suitable for installation in zones 1 and
21 and, even more so, in zones 2 and 22 as classified in enclo-
sure I of Directive 99/92/EC.
The relief valves described here are not suitable for use in zones
0 and 20 as defined in Directive 99/92/EC.
To determine the qualification and extension of the hazardous
zones, see standard EN 60079-10.
If installed and maintained as per the conditions and instructions
given in the enclosed technical manual, the relief valve is not a
source of specific danger.
In particular, under normal operating conditions, the device only
rarely emits inflammable substances such as to generate an
explosive atmosphere.
The relief valve has a work membrane and a safety membrane;
if the work membrane breaks, the safety membrane guarantees
gas emission with flow rate no higher than 30 dm
3
/h. A continu-
ous explosive atmosphere able to generate a hazardous zone 0
is emitted solely in the event both membranes break simultane-
ously.
In the event the valve is installed in an unmanned or poorly aired
location, all the necessary precautions should be taken to prevent
the valve from being the cause of a zone 0.
For example, the breather may be routed outside via a copper
pipe connected to the threaded hole G1/8” by removing the
dustproof brass cap.
The valve may be assembled in a variety of positions; on horizon-
tal piping it is advisable to keep the valve sleeve facing upwards.
The following guidelines should be followed:
• do not lever on the sleeve when assembling the valve;
• ensure that the piping is well aligned and that there are no
obstructions or dirt inside;
• observe the flow direction as shown by the arrow printed on
the valve body;
• check that all pressure, temperature etc. parameters are com-
plied with;
• do not install the valve in contact with plastered walls.
The relief valve should be installed upstream of the pressure
regulator.
Calibration
1. Check that all the utilities are off.
2. Screw down the relief valve adjusting screw completely.
3. Slowly open the on/off valve upstream of the system.
4. Increase the pressure downstream of the regulator by turning
the adjusting screw until the required pressure for the breather
is reached.
5. Slowly unscrew the relief valve adjusting screw until gas begins
to escape.
6. Restore the initial regulator outlet pressure.
7. Screw on the plastic safety caps on the screws that adjust the
regulator and the relief valve.
Maintenance
The relief valves do not require any special maintenance. In the
event of a fault, run a general overhaul and relative test on site.
Periodically check the working efficiency of the entire safety sys-
tem by increasing the regulator pressure until the device is trig-
gered.
If the valve must be disassembled for any reason, make sure
there is no pressure in the circuit.
ALL INSTALLATION, CALIBRATION AND MAINTENANCE
OPERATIONS MUST BE CARRIED OUT SOLELY BY
QUALIFIED PERSONNEL.
The descriptions and photographs contained in this product specification sheet are supplied by way of information only and are not binding. Watts Industries reserves the right to carry out any
technical and design improvements to its products without prior notice. Warranty: All sales and contracts for sale are expressly conditioned on the buyer’s assent to Watts terms and conditions
found on its website at www.wattswater.eu. Watts hereby objects to any term, different from or additional to Watts terms, contained in any buyer communication in any form, unless agreed
to in a writing signed by an officer of Watts.
RELIEF VALVES
