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Frequently Asked Questions

What is an excess flow valve?

An excess flow valve is a mechanical device installed inside a natural gas distribution service line between the street and residential meter that enhances the safety of your natural gas service.  If there is a significant increase in the flow of natural gas (e.g., due to a damaged line), the EFV will “trip” or close to minimize the flow of gas through the service line. Once the repair is made and the correct pressure is restored, the EFV automatically resets itself.

Note that an EFV cannot protect against certain leaks on the service line or meter such as those caused by corrosion or loose fittings. It also cannot protect against leaks beyond the natural gas meter, for example, natural gas piping inside the premises and also at or near appliances.

While the pipelines serving your community are already safe, federal code changes require that we let customers know about this supplemental device.  Note that an EFV is not required on existing natural gas service pipelines.

Much like a backup camera in a newer car model, an EFV is an enhancement to your already-safe natural gas service pipeline.


How do I know if I have an excess flow valve?

Typically single family homes built since the year 2005 have an EFV installed on the natural gas service line. If your home was built before then, it is likely that there is not one installed. To verify, complete our request form and a representative will contact you about your inquiry.


How do I know if an EFV can be installed at my premises?

In some instances, due to system operating characteristics, excess flow valves cannot be installed. If this is the case, we will let you know in response to your request.


If I want one installed, what should I do?

If you’d like to have an EFV installed on the natural gas service line at your premises, please complete our request form and someone from Nicor Gas will reach out to set up an appointment.


Is there a cost to have an EFV installed at your request?

Yes. There is a fee of about $2,200 to have an excess flow valve installed on the natural gas service line at your premises. This charge will not appear on your monthly Nicor Gas bill. Instead, you will receive a separate bill, mailed to your billing address, for the installation charge.