Excess Flow Valves (EFV's)
Excess Flow Valves (EFV's) are installed on single family
residential service lines.
|What is an Excess Flow Valve
An EFV is a mechanical safety device installed in conjunction
City's gas service line. In the event of damage to the
City's gas service line between the street and your meter, the
EFV will "trip", minimizing the flow of gas through the service
line and reducing the amount of gas vented to the atmosphere.
|How do Excess Flow Valves
A spring pushes a valve open against the oncoming gas flow.
Sensing a change in pressure, the spring forces valve closed,
minimizing the flow of gas. EFV's are designed so that when
you turn on your gas appliances, the flow isn't enough to push
the valve shut, however, if the line is damaged, there is enough
flow to push the valve shut. After the EFV trips, the gas
pressure continues pushing on the valve, keeping the valve
closed until the correct pressure is restored by the City.
When lines are repaired and service is restored, the valve
automatically resets itself.
|How will an Excess Flow Valve
(EFV) affect my gas service?
Your EFV may affect your gas service if the service line is
damaged. A small puncture of the service line typically
won't trip the EFV, it requires significant damage to
activate. There will not be any blowing gas to identify that a
line has been damaged, but there will typically be enough gas to
indicate a gas odor. To report a
damaged service line or if you smell gas in or outside of your
home, call 480-644-4277 (GASS).
The EFV and gas meter installed at your house was sized based
on the homes gas appliance load. If you add additional gas
appliances such as a barbeque, pool/spa heater, or fire pit, the
additional gas appliances may make your total gas demand too
high for your current gas meter and may affect the operation of
Prior to installing additional gas appliances, contact Mesa's
Development and Sustainability Department at
480-644-4273 (select option 1 for English, then select option 1,
Building Permits/Right of ways) to check if your meter can handle the
additional load. If you need a larger meter, we will
schedule an appointment and install the appropriate meter during regular
business hours at no additional charge. If it is determined the EFV also needs to
be upgraded, it will also be replaced.
Remember, prior to any excavation
project, call the Arizona Blue Stake Center
at 811 to have your underground utilities located.
PO Box 1466
Mesa, AZ 85211
Gas Emergency or Odor
480-644-4277 (GASS) or 911
(24 hours/7 days)
480-644-2266 or 911
(24 hours/7 days)
Report Utility Theft
Monday - Thursday
7 a.m. to 6 p.m.
Frank McRae, Department