Pumps in gas stations normally have a "lock" on the handle that allows
an individual to fuel the vehicle without continually squeezing the
pump handle lever.  In Massachusetts, 90% of the self-serve gasoline
stations have this lock pried off.  I assume either a law or
regulation requires this.

What is the law or regulation?  What is the purpose of this law or
regulation?

Hi Shawmut,

Good observation!

The issue with locks on the nozzles of gasoline pumps has to do with
spark-induced fires caused by people locking the nozzle, getting back
into their cars, building up static electricity by rubbing against the
upholstery of the seat, then getting back out and grasping the nozzle.
 To date over 150 refueling fires have been documented that appear to
be caused by a discharge of static electricity.

Being unable to lock the nozzle in the open position and leave it
precludes you from getting back into the car where you are likely to
buildup static electricity.

This Petroleum Equipment Institute report should explain everything
you need to know about the issue:

STOP STATIC: a safety campaign to increase public awareness of the
potential danger posed by the discharge of static electricity during
refueling.
http://www.pei.org/static/


SUMMARY OF FIRES AT REFUELING SITES THAT APPEAR TO BE STATIC RELATED
http://www.accidentreconstruction.com/newsletter/jul02/gaspump2.asp


Although not all states have laws requiring the removal of the
hold-open latches on gas pump nozzles, many gas station owners have
removed them voluntarily.

In Massachusetts the Law states thus:


SECTION 5.08:   
  (k)   Hold open clips shall not be allowed on self-service
dispensing nozzles.



527 CMR 5.00:  OPERATION AND MAINTENANCE OF BUILDINGS OR OTHER
STRUCTURES USED AS GARAGES, SERVICE STATIONS AND THE RELATED STORAGE,
KEEPING AND USE OF GASOLINE OR OTHER MOTOR FUEL
http://216.239.39.104/search?q=cache:iguLZzDXv3YJ:www.state.ma.us/dfs/cmr/527005.doc+site:www.state.ma.us+gasoline+pump&hl=en&ie=UTF-8


So all self-service stations in MA *should* have the clip removed. 

For more information on this topic, see this question that I
previously answered.


Subject: Gas station explosions
http://answers.google.com/answers/main?cmd=threadview&id=60954


Thanks for your question!

-K~


searched: site:www.state.ma.us "hold open clip"

Howdy shawmut!

To hopefully add to knowledge_seeker-ga's (as always) great
answer.

There is also the problem of "unattended pumping" wherein the
overflow protection of the pump will not operate as it should,
and you end up with 10 gallons of gas all over the place.

Looking Forward, denco-ga

Thanks knowledge_seeker and denco.  

Five engineers sitting around a room generated five different answers,
all emphatically asserting their answer was correct.  The answers
ranged from gas stations selling foodstuffs could not have a hold open
clip for sanitary reasons (?), to the hold open clips interferring
with the EPA mandated vapor recovery system on Massachusetts pumps, to
simple vandalism, to overspill reduction.  My google search was
fruitless, and I inadvertently discovered google answers by adding a
question mark to my query.

Knowledge_seeker quickly provided the definitive answer. 
Knowledge_seeker rules!