STATUS REPORT

ON

GAS-FIRED WATER HEATER IGNITION

OF

FLAMMABLE VAPORS

October, 1996

For Additional Information Contact:

Donald W. Switzer

Directorate for Engineering Sciences

(301) 504-0508 ext.1303

NOTE: This documrn! h.: not becIr n CPSA 

reviewed or acce;p!tir .2; the Co'nmii-ion. ,

aInituial . l-l- f U -Do' Products Identified

Excepted by

Firms Notified, _-- . r .~ --. J

EE-RM-97-900 COMMENT 01G
United States

CONSUMER PRODUCT SAFETY COMMISSION

Washington, D.C. 20207

MEMORANDUM

DATE: OCT I 5 1996

TO The Commission

Sadye E. Dunn, Secretary

Through Eric A. Rubel; General Counsel

Pamela Gilbert, Executive Director )~

FROM Ronald L. Medford, Assistant Executive Director k.lt

for Hazard Identification and Reduction

Donald W. Switzer, Chemical Engineer, ESEE (504-0508 ext. 1303) j_'

SUBJECT Status Report on Gas-Fired Water Heater Ignition of Flammable Vapors

1. Purposr

This status report updates the Commission on industry activities to develop voluntary

standard requirements to address the hazard posed by gas-fired water heaters igniting

flammable vapors.

2. Background

Gas-fired water heaters igniting flammable vapors

cause an estimated 1,961 fires each year resulting in an

estimated 316'injuries, 17 deaths, and $26 million in property

damage for a total societal cost which may be as high as $395

million. Typically, injuries occur when the victim is using

flammable liquids (usually gasoline) for cleaning purposes, or

when the liquid leaks or is accidentally spilled near the water

heater. Current water heater designs take combustion air

from near the floor. When the burner ignites, the vapors in

the room are swept into the water heater and ignited (Fig. 1), /

which can cause a flashback fire or explosion.

On December 15, 1994, Chairman Ann Brown Figure 1

directed the staff to work with the industry to develop the

NOTE: This document has not been CPSA 6 (b)( Cle d 

reviewved or accepted hb the Commnision, /

Lnitial hJ- Date_ tN I- P ::. : Or

Prod'.llct '-

EE-RM-97-900 COMMENT 01G
necessary standards requirements to address the hazard and to provide periodic progress

reports. In the last status report, dated March, 1996, staff reported to the Commission that

industry progress was satisfactory.

3. Evaluation of Industry Activities

Industry has initiated two activities to address the flammable vapor ignition issue. The

first is a program to develop a performance test methodology to evaluate water heater designs

for resistance to flammable vapor ignition. This activity is the primary focus of this status

report. The second activity is development of proprietary new designs to reduce the potential

for flammable vapor ignition.

3.1 Status of Test Methodology Development:

The goal of developing a performance test methodology is to have uniform criteria

against which to evaluate a water heater's resistance to flammable vapor ignition. Ultimately,

all residential storage type water heaters will be design certified against these new criteria.

In July, 1996, the Gas Research Institute (GRI) published the final report on the

methodology development project begun in October 1994. The purpose of the project was to

develop a test methodology to form the basis for specific standard requirements to be included

in the American National Standards Institute (ANSI) Standard for Gas-Fired Water Heaters,

ANSI Z21.10.1. In the March, 1996, Status Report, staff reported that a total of $1.4

million had been allocated for standards development activity. GRI has increased the amount

allocated for this project to approximately $2.0 million to provide additional technical support

to the voluntary standards activity, and to support field testing of products.

CPSC staff participated in developing the test methodology, and believes it to be very

stringent. The approach being taken is to inject butane vapors into a chamber containing the

water heater tightly controlling the vapor cloud height to represent different spill scenarios. A

water heater is then operated in the chamber. The appliance is cycled through all its

operating conditions including main burner off, main burner on, and cycling. Burner

operations are controlled by drawing hot water off the appliance as done in the home. If, at

any time during the test, the vapors are ignited, the design fails the test. It is, in staffs view,

highly unlikely that a water heater certified to this test methodology would ignite vapors in the

home. The methodology has been presented for review to the Flammable Vapor Working

Group of the ANSI water heater subcommittee.

The new technologies being developed may incorporate features that will require

changes to the standard in addition to the vapor ignition tests. At present, the new

technologies are not sufficiently mature to determine the exact modifications that will need to

be included in the standard. To facilitate this portion of the standard revision, those

manufacturers involved in developing ignition resistant technologies have agreed to use the

proposed test methodology in their product design testing. This serves both to assure that the

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new technologies will be able to pass the final test, and to generate experience using the test

methodology. Water heater manufacturers have agreed to coordinate their comments on the

draft standard provisions through the Gas Appliance Manufacturers Association (GAMA).

This will allow different manufacturers with different technologies to coordinate their

comments without revealing proprietary information to their competitors.

GAMA will present the recommended changes to the Flammable Vapor Working

group at its next meeting, tentatively scheduled for early 1997. This timing is necessary to

allow time for additional product development testing, fine tuning the methodology, and

identifying other necessary changes to the standard. At that time, staff expects that the major

recommended changes to the standard will be adopted. Once the working group has

completed developing its recommendations, they will be forwarded to the full ANSI water

heater subcommittee for adoption as a draft standard. The water heater manufacturers who

sit on the subcommittee are developing the recommendations and CPSC staff expects that the

draft test method will have overwhelming manufacturer support at the subcommittee level.

Since the utilities have also been involved in developing the test methodology, CPSC staff

expects support from that quarter as well. Manufacturers estimate it will require 30 months,

including industry review and public review, to finalize the revisions from the time the test

methodology is forwarded to the Flammable Vapor Working Group. Based on that estimate,

CPSC staff currently expects that the revised standard incorporating vapor ignition protection

will be sent to ANSI in 1999 for approval as a national standard.

3.2 Status of Product Development:

In spring, 1995, several water heater manufacturers formed the Water HeaterJoint

Research and Development Consortium to develop vapor ignition-resistant water heaters as

quickly as possible. Specifics of the product development activities are confidential and are

not discussed in this report. The work to date is within the confidential product development

schedule provided to the Commission in December, 1994.

4. Conclusions

Staff concludes that industry progress in developing performance requirements for new

vapor ignition-resistant water heater designs continues to be satisfactory. A sophisticated test

methodology has been developed and appears acceptable to the staff. Barring unforeseen

difficulties, a standard test method for resistance to flammable vapor ignition is expected to

be available on schedule, before new design water heaters are in production. Staff also views

the progress in developing new technology water heaters as satisfactory.

Staff will continue to provide the Commission with written status reports every six

months, or at any point if problems develop or progress becomes unsatisfactory. Staff will aiso

report to the Commission if product development is delayed.

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