A History of Fire Sprinklers

In 1812, British inventor Sir William Congreve patented a manual sprinkler system using perforated pipes along the ceiling. When someone noticed a fire, a valve outside the building could be used to send water through the pipes.

Henry S. Parmalee of New Haven, CT created and installed the first automatic fire sprinkler system in 1874, using solder that melted in a fire to plug holes in the otherwise open water pipes. At the time he was the president of Mathusek Piano Works. Parmelee invented his sprinkler system in response to exorbitantly high insurance rates. Parmelee patented his idea and had great success with it in the U.S. Parmelee called his invention the "automatic fire extinguisher". He then traveled to Europe to show people that there was finally a way to help stop a building fire before everything was destroyed.

His invention did not get as much attention as he had planned. Most people could not afford to install a sprinkler system. Once Parmelee realized this, he turned his efforts on educating the insurance companies about his system. He talked about how the sprinkler system would reduce the loss ratio, thus saving money for the insurance companies. He knew that he could never succeed in obtaining contracts from the business owners to install his system unless he could at the same time ensure for them a reasonable return in the shape of reduced premiums.

In this connection he was fortunate enough to enlist the sympathies of two men, who both had connections in the insurance industry. The first of these was Major Hesketh, who, in addition to being a cotton spinner in a large business in Bolton, was Chairman of the Bolton Cotton Trades Mutual Insurance Company. The Directors of this Company and more particularly its Secretary, the late Peter Kevan, took an interest in Parmelee’s early experiments, and eventually it was to Major Hesketh, its Chairman, that Parmelee owed his first order for the Sprinkler Installations which were installed in the Cotton Spinning Mills of John Stones & Company, at Astley Bridge, Bolton, to be followed soon afterwards by the Alexandra Mills belonging to Mr. John Butler of the same town.

Although he got a contract through his efforts, the Bolton Cotton Trades Mutual Insurance Company was not a very big company outside of its local area. Parmelee needed a wider influence. He found this influence in James North Lane, the Manager of the Mutual Fire Insurance Corporation of Manchester. This company was founded in 1870 by the Textile Manufacturers' Associations of Lancashire and Yorkshire as a protest against high insurance rates. They had a policy of encouraging risk management and more particularly the use of the most up-to-date and scientific apparatus for extinguishing fires. Even though he put tremendous effort and time into educating the masses on his sprinkler system, by 1883 only about 10 factories were protected by the Parmelee sprinkler.

Back in the U.S., Frederick Grinnell, who was manufacturing the Parmelee sprinkler, designed a newer and more effective version which became known as the Grinnell sprinkler. He increased sensitivity by removing the fusible joint from all contact with the water, and, by the ingenious method of seating a valve in the center of a flexible diaphragm, he relieved the low fusing soldered joint of the strain of water pressure. By this means the valve seat was forced against the valve by the water pressure, producing a self-closing action, so that the greater the water pressure, the tighter the valve. The flexible diaphragm had a further and most important function. It caused the valve and its seat to move outwards simultaneously until the solder joint was completely severed. Grinnell got a patent for his version of the sprinkler system. He also took his invention to Europe, where it was a much bigger success than the Parmelee version. Eventually, the Parmelee system was withdrawn, which left an open path for Grinnell and his invention.

Wet Systems

Description

A wet pipe sprinkler system is fixed fire protection using piping filled with pressurized water supplied from a dependable source. Closed heat sensitive automatic sprinklers spaced and located in accordance with recognized installation standards are used to detect a fire. Upon operation, the sprinklers distribute the water over a specific area to control or extinguish the fire. As the water flows through the system, an alarm is activated to indicate the system is operating. Only those sprinklers immediately over or adjacent to the fire operate, minimizing water damage.

Applications

A wet pipe sprinkler system may be installed in any structure not subject to freezing to automatically protect the structure, contents, and/or personnel from loss due to fire. The structure must be substantial enough to support the piping system filled with water. Using water as its extinguishing agent, one wet system may cover as much as 52,000 square feet in a single fire area. The system should be designed by qualified fire protection engineers in conjunction with insuring bodies. Sprinkler systems are engineered to meet the standards of National Fire Protection Association, Factory Mutual, Loss Prevention Council or other similar organizations, and also with the provisions of governmental codes, ordinances, and standards where applicable. Small unheated areas of a building may be protected by a wet system if an antifreeze-loop or auxiliary dry system is installed.

Dry Systems

Description

A Dry Pipe Sprinkler System is a fire-protection system which utilizes water as an extinguishing agent. The system piping from the Dry Pipe Valve to the fusible sprinklers is filled with pressurized air or nitrogen. An air check system is a small dry system which is directly connected to a wet pipe system. The air check system uses a dry valve and an air supply, but does not have a separate alarm. The alarm is provided by the main alarm valve.

Applications

A Dry Pipe System is primarily used to protect unheated structures or areas where the system is subject to freezing. Under such circumstances, it may be installed in any structure to automatically protect the structure contents and/or personnel from loss due to fire. The structure must be substantial enough to support the system piping when filled with water. One system may protect as much as 52,000 sq. ft. (4830.8m2) in a single fire area. The system should be designed by qualified fire protection engineers in conjunction with insuring bodies

Operation

When a fire occurs, the heat produced will operate a sprinkler causing the air pressure in the piping system to escape. When the pressure trip-point is reached (directly or through the ac-celerator), the dry-pipe valve opens allowing water to flow through the system piping and to the water motor alarm or electric pressure switch to sound an electric alarm. The water will continue to flow and the alarm will continue to sound until the system is manually shut off. A dry-pipe valve equipped with an accelerator will trip more rapidly and at a higher air-pressure differential. Component parts of the dry-pipe system operate in the following manner:

A. Dry Valve Operation
When the air pressure in the dry system has dropped (from the fusing of an automatic sprinkler) to the tripping point of the valve, the floating valve member assembly (air plate and water clapper) is raised by the water pressure trapped under the clapper. Water then flows into the intermediate chamber, destroying the valve differential. As the member assembly rises, the hook pawl engages the operating pin which unlatches the clapper. The clapper is spring-loaded and opens to the fully opened and locked position automatically.

B. Accelerator Operation
The accelerator operates on the principal of unbalanced pressures. When the accelerator is pressurized, air enters the inlet, goes through the screen filter into the lower chamber and through the anti-flood assembly into the middle chamber. From the middle chamber the air slowly enters the upper chamber through an orifice restriction in the cover diaphragm. In the SET position the system air pressure is the same in all chambers. The accelerator outlet is at atmospheric pressure. When a sprinkler or release operates, the pressure in the middle and lower chambers will reduce at the same rate as the system. The orifice restriction in the cover diaphragm restricts the air flow from the upper chamber causing a relatively higher pressure in the upper chamber. The pressure differential forces the cover diaphragm down pushing the actuator rod down. This action vents the pressure from the lower chamber to the outlet allowing the inlet pressure to force the clapper diaphragm open. The pressure in the accelerator outlet forces the anti-flood assembly closed preventing water from entering the middle and upper chambers. On a dry pipe system the air pressure from the accelerator outlet is directed to the dry pipe valve intermediate chamber. As the air pressure increases in the intermediate chamber, the dry valve pressure differential is destroyed and the dry valve trips allowing water to enter the dry pipe system. On a pneumatic release system, the outlet pressure is vented to atmosphere, speeding the release system operation.

Preaction Systems

General Description

There are several types of preaction systems, but all employ closed sprinklers in the sprinkler piping.The detection system may be hydraulic, pneumatic or electric, and may be actuated by manual, fixed-temperature, rate-of-temperature-rise or other means. Detection systems operate before the sprinklers fuse and give an alarm. Because preaction systems are often used in freezing areas, electrical and pneumatic detection systems are by far the most common. Preaction systems are usually supervised. The purpose of supervision is to monitor the integrity of the system. Air or gas under pressure is maintained in the sprinkler and release piping. If the sprinkler or release piping or a sprinkler head is broken, the pressure will be reduced and an alarm will sound. There will also be an alarm due to low air or gas supply pressure. Electrical equipment can be similarly supervised. Hydraulic release system or supply pressure may also be supervised.

Types of Applications

Preaction systems operate in several of ways and perform a variety of functions. A summary of the most common types of preaction systems follows:

Non-Interlock Preaction System:This preaction system utilizes a Viking deluge, which may be opened either by the fusing of a sprinkler in the sprinkler piping or by the operation of the detection system. The sprinkler piping contains air or gas under pressure. If the detection system does not operate, the sprinkler system will operate as a dry pipe system. If the sprinkler piping is broken or the sprinkler operates, the valve will open and water will flow. If the detection system operates due to fire, damage, or malfunction, the valve will open, but the water will be contained in the sprinkler piping. The system is supervised to indicate low air pressure. The objective of this system is to fill the sprinkler piping with water prior to the fusing of a sprinkler, thereby permitting more rapid fire attack.

Single-Interlocked Preaction System:The single interlocked preaction system requires operation of the detection system to trip the Viking deluge valve and fill the system with water. It also utilizes supervisory air pressure in the system piping. Water will then be discharged on the fire when the sprinklers fuse. If the sprinkler piping or sprinkler is broken, a supervisory alarm will sound, but the valve will not open. If the detection system operates due to fire, damage, or malfunction, the valve will open, but the water will be contained in the sprinkler piping. If the detection system does not operate, the valve will not open.

Supervision is generally used since control of accidental discharge is usually desired. The single interlocked preaction system is commonly used where it is desirable to have water available at the sprinkler when the sprinkler fuses and where the sprinkler piping is subject to damage. The most common applications are very large dry systems that exceed the capacity normally permitted on a dry valve and in a system application where it is important to control accidental water discharge due to damaged sprinkler piping.

Double-Interlocked Preaction System:The Double-Interlocked Preaction System utilizes a detector system and pressurized air or gas in the sprinkler piping. This system utilizes the Viking deluge valve and is arranged so that the valve will open only when both pressure reduced in the sprinkler piping and the detection system operates. If the detection system operates due to fire, damage, or malfunction, the valve will not open, but an alarm will sound. If the sprinkler piping is damaged or sprinkler is broken or fused, the valve will not open but a supervisory alarm will sound. The operation of both a sprinkler and a detector (or release) is required before the valve will open, allowing water to enter the system piping.

Because pressurized air or gas is available in the output piping, the system is usually supervised.The Double-Interlocked Preaction System is commonly used in freezers where flooding of the pipe can have serious consequences and in system applications where it is important to control accidental discharge of the system.

Deluge Systems

1. Description

A Deluge System is a fixed fire-protection system which totally floods an area with pressurized water through a system of piping and open nozzles or sprinklers. The system piping is empty until the deluge valve is activated by a hydraulic, pneumatic, electric or manual release system.

2.Applications

Regular deluge systems may be required to protect extra-hazard occupancies by creating a fire buffer zone or by cooling surfaces to prevent deformation or structural collapse. Examples: storage or process areas containing substances having a low flash point; areas in which fire may spread rapidly; tanks containing combustible solutions, transformers, equipment pits or product handling systems. Systems should be designed by qualified fire-protection engineers in conjunction with the approving bodies having jurisdiction.

Foam-water deluge systems are those using foam-water sprinklers or spray nozzles and an air-foam concentrate which is introduced into the water at controlled rate on the system side of the deluge valve. Foam water systems are used to control and/or extinguish fires which require a smothering and cooling agent. Examples: extraction plants, aircraft hangars and areas where flammable-liquid spill fires may occur.

3.Operation

The deluge valve prevents water from entering the system piping until required. The deluge valve is kept closed by a pressurized upper valve chamber. The pressure is maintained through a restriction on the service side. This upper chamber is also connect¬ed to the release line. When the pressure is relieved from the upper chamber through the release line, the clapper is lifted by the water pressure under the clapper. Water floods the system and rings alarm.