Note: Earthquake Actuated Valves and Excess Flow Valves should be certified by the State Architect. Some installations may require building permits (consult your local jurisdiction). Some juridictions have adopted ordinances requiring gas shutoff devices at time of sale or when significant renovations are being undertaken.

Gas Shut-off Option Costs (prices are approximate and vary depending on the city in which you live)
device 1	hardware cost	installation cost 2
Restrain Individual Gas Appliance	$15-$50	$0-$100
Manual Shutoff valve & wrench	$5-$20	$0
Earthquake actuated valve	$100-$300	$100 - over $300 3, 4, 5
Excess flow valve at meter	$20-$100	$100 - over $300 3, 4
Excess flow valve at appliance	$5-$15	$0-$100
Methane Detector	$25-$75	$0
Hybrid system	$150-over $500 6	$100 - over $500 7

Notes:

1. There are significant differences in the operaton of the various devices listed.
2. All costs are approximate and do not include permit and inspections fees that may range from $25 to over $100 depending upon the local jurisdiction. Installations that can be performed by the building owner are assumed to have no cost.
3. Installation costs do not include a survey of the gas system that can cost over $200.
4. Higher installation costs may occur if substantial modifications of plumbing are necessary.
5. Higher installation costs may occur if substantial modifications to attach the valve to the building are necessary.
6. Costs for hybrid systems depend on the number and type of components installed.
7. Higher installation costs can be incurred for hybrid systems that require installation of wiring to connect multiple sensing units.

Gas Shut-Off Comparisons
consideration	manual shut-off valve and wrench	earthquake actuated valve	excess flow valve	methane detector	hybrid system
basis of operation	Utilities have installed manual shutoff valves near gas meters allowing owners with proper wrenches to shutoff gas in emergencies	Senses shaking in a building that is above a design level of shaking and automatically shuts off gas.	Senses gas flows that are above a design shutoff flow rate and automatically shuts off gas.	Senses the presence of natural gas in the air and triggers an alarm.	A variety of modular devices that could include a main control unit, shake sensors, excess flow sensors, methane detectors, and alarms.
benefits	All gas services already have valves installed. Guidance for occupants is currently provided in many public information documents like the phone book.	Actuates only in cases when building shaking may be sufficient to cause damage to the gas system. Someone does not need to be present to ensure shutoff.	Actuates only in cases when excess gas flows downstream of the device. Someone does not need to be present to ensure shutoff.	Alerts occupants when detectable gas concentrations are present they reach hazardous levels, allowing time for shutoff and evacuation.	Systems are modular and can be customized for desired applications. Each module has benefits associated with specific action.
potential drawbacks	Only effective if someone is present, knows the valve location, has access to the valve, and has a wrench suitable to close the valve.	Can actuate even if damage and hazards do not exist. Aftershocks can cause the device to actuate after service has been restored. May actuate from shaking not related to earthquakes.	Will not shut off gas if leakage is below the design shutoff flow rate, even if a slow leak exists. May not activate if the occupant changes gas systems downstream without modifying the device.	Someone needs to be present to respond to the alarm. Alarm may trigger for other flammable vapors in addition to natural gas.	Each module has drawbacks associated with specific actions.