Model 750 Gas Meter
Installation, Commissioning and Maintenance Manual
Page 9 of 17
© Gyr
17-May-2016
Due to continuous product development the details above are subject to change without notice. Whilst Gyr has taken all reasonable
care in reviewing the information in this document, Gyr makes no representations in respect of, gives no guarantees or undertakings in
relation to, and to the maximum extent permitted by law, excludes all warranties in relation to, the accuracy or completeness of the information
in this document. Prospective users of this information should make their own enquiries as to its accuracy and reliability.
ensure that the maximum operating pressure of the
meter is not exceeded.
When the meter is used with gases high in
contaminants it is recommended that a suitable filter is
installed on the inlet side of the meter.
A suitable stop valve should be installed before the
inlet of the meter for maintenance purposes.
Avoid installing the meter in locations where the meter
casing is in direct contact with soil or concrete walls.
Alkali in concrete as well as other corrosive elements
in soil can cause premature corrosion of the meter
casing.
3.
Pipe Work Installation
Ensure that installation pipe work is thoroughly clean.
Foreign materials such as pipe scale, rust flakes,
excessive plumbing tape, excessive thread sealant
must be removed prior to installing the meter.
The gas meter, weighing 2.7 kg, can be supported
entirely by the meter bosses. It is typical for the meter
to be suspended by pipe work alone.
The installer shall ensure that the pipe work
does not result in excessive forces being
applied to the meter bosses. The suitability of
the pipe work is the responsibility of the installer.
The gas meter should be installed as close to level as
possible in order to ensure accurate operation. The
pipe work shall be in line with the meter bosses and
not forced into position. The direction of gas flow must
correspond to the arrow marked on the meter body.
Hand tighten the inlet and outlet swivel cap. Using a
pipe wrench, alternate between both swivel caps nuts
and tighten approximately three flats (approximately
15 - 25 Nm). DO NOT OVER TIGHTEN. Damage to
the rubber gasket inside the swivel cap nut may result.
PUTTING INTO OPERATION
Before turning the gas on, check the system down-
stream of the meter to be sure that all connections are
made up and tight or that the downstream valve, if
there is one, is closed.
CARE must be taken to prevent excessive
flows and high pressure drops across the
meter.
If CARE is not exercised when pressurising the meter
over-speeding of the meters internal mechanism may
result in internal damage to the meter. To prevent
over-speeding the pressure drop across the meter
should not exceed 125 Pa or (0.
5” wc). This can be
achieved by pressurising the meter and the
downstream pipe volume to appliances as slowly as is
possible.
To avoid high differential pressure across the meter,
open the upstream and downstream valves VERY
SLOWLY to prevent any pressure surges into or out of
the meter.
4.
Check For Leaks
Check for leaks and check all connections for
tightness. Repair all leaks as required.
Use liquid leak detector to check for leaks at the pipe
connections.
5.
Turn On Appliances
All air or inert gases should be safely purged
from the downstream piping before any
attempt is made to light an appliance.
Appliances should then be started as per the relevant
appliance manufactures procedures.
SPECIAL NOTE FOR BOTTLED OR TANK LPG
GAS SYSTEMS
Bottled or tank gas cylinders contain pressures of
several thousand kPa and the Model 750 can be
supplied as a high pressure version up to 150 kPa.
This disparity means that the bottled or tank gas
system (which includes regulators, relief valves and
over pressure devices) must ensure that the
maximum operating pressure of the meter is not
exceeded.
When tank filling or connecting fully pressurised
bottled gas cylinders into an empty or near empty
system
EXTREME CARE
must be taken not to
overload the regulator diaphragms with a sudden
surge of inlet pressure (of several hundred to
thousands kPa).
So called “Change-Over” regulators used in the
changing of cylinders are particularly susceptible to
this problem, when the gas pressure is low.
This can result in an increase in outlet pressure
greater than that of the maximum operating pressure
of the meter and create high differential pressures
across the meter. This can result in damage to the
meters diaphragms and/or internal mechanism.
To avoid high differential pressures across the
meter and/or pressures exceeding the
maximum operating pressure of the meter,
pressurise the system
VERY
SLOWLY
to prevent any
pressure surges into the system.
INSPECTION & MAINTENANCE
6.
Inspection Frequency
A properly installed and commissioned meter should
provide many years of trouble free operation, however
