AUTHOR: Steve Coolidge - CGI

Blow-off caps on wet chemical extinguishing systems made of rubber material often fail to stay in place up to 60% of the time according to industry sources. This exposes the tip of the nozzle and allows grease to enter. The tip then becomes clogged with grease baked in by heat from cooking equipment.

Ansul, Amerex and Pyrochem normally use rubber blow-off caps for their systems as base nozzle protection. Range Guard uses factory installed nozzle seals fitted with a chrome screw. This second type is less likely to fail under normal use.

Metal caps complete with a wire clip are available from each of the above suppliers as an option. These metal blow-off caps are more expensive than the rubber variety.

Responsibility rests with restaurant owners to ensure that whatever type of cap is used, the maintenance or housekeeping department keeps them in place. Our field survey experience suggests that in many instances, the restaurant staff or manager on duty (MOD) ignore this simple fire safety need. They appear to place little or no emphasis on ensuring the caps are in place or are replaced as necessary due to failure from heat and grease.

While cooking appliance nozzles are readily seen, other nozzles behind the filters are less likely to be looked at. Any nozzles using rubber caps situated above the filters in the plenum and ductwork are even more susceptible to discovery. The opportunity to discover cap failure falls sharply in these areas because of their locations and heavier grease accumulations plus greater difficulty accessing the space. These nozzles are far more likely to become grease clogged when left unprotected by a cap. The result is that a clogged nozzle most likely will not discharge in the event of a fire.

Education is the key to ensure that blow-off cap failures do not indirectly result in bodily injury, death and property damage under fire conditions.

Relying strictly on the service companies who come in every six months to service the systems and replace the blow-off caps is not practical. It is not an adequate solution to ensure that your wet chemical fire protection system will properly function in the event of a fire. A nozzle tip can easily become clogged within that six month period.

Owners and operators should make recommendations in writing to each location or operation equipped with wet chemical fire extinguishing systems to maintain blow-off caps in position. It is a matter of education to advise them that blow-off caps are important and need to be maintained and mounted.

Especially when caps have been off for a period of time, the nozzle orifice should be inspected for grease accumulation or possible clogging. Should the nozzle appear to be clogged, the service company should be notified, then cleaned or replaced.

Suppliers and installers of wet chemical kitchen extinguishing systems have an obligation to educate the users of their systems. Users must be continually reminded of the importance and function of blow-off caps. Failure to do so could result in serious financial loss, injury or loss of life all leading to potential litigation.

Only Ansul and Amerex use retainer type rubber and steel caps. Rubber caps have a one year service life. Their temperature limit is 360 degrees F. or lower. If the rubber is not flexible, they must be replaced at the six month servicing. Ansul requires a thin layer of Dow Corning 101 silicone grease be applied to the nozzle orifice at each inspection. The purpose is to help prevent internal contamination of the nozzle.

Pyro Chem uses a steel cap with no retainer. The cap is held in place with an internal o-ring and appear to be quite effective. Very few of this type are noted missing during inspections.

Range Guard and Kidde both use a foil seal that is easily punctured. The punctured seal loses protection and can lead to a plugged nozzle.

Replacement caps are purchased in bulk ranging from 10 to 50 per box depending on the type and the supplier. These include steel, rubber, steel nut and foil seal varieties.

The main challenge is education. Kitchen staff especially those not educated on the value of blow-off caps are more likely to toss them in the garbage when found hanging off the system nozzles. Educate, educate, educate.

This information is for educational purposes only and must not be published without the consent of the writer. Please contact Steve Coolidge for permission to publish this material. The content of this advisory is not intended to suggest that the manufacturers, suppliers or installers of blow-off caps have failed to meet the codes and standards of any jurisdiction.

Steve Coolidge , CRM, SFPE
Manager, Loss Control
CGI Insurance Business Services
ISO 9001 Registered
PHONE: 403-296-6452
Fax: 403-296-6450
EMAIL: steve.coolidge@cgi.com