Frequently Asked Questions

Backflow is the undesirable reversal of flow of water or other substances through a cross-connection and into the piping of a public water system or consumer’s water system. There are two types of backflow, backpressure and backsiphonage.

Backpressure backflow is backflow caused by a downstream pressure that is greater than the upstream or supply pressure in a public water system or consumer’s potable water system.

Backpressure (i.e., downstream pressure that is greater than the potable water supply pressure) can result from an increase in downstream pressure, a reduction in the potable water supply pressure, or a combination of both. Increases in downstream pressure can be created by pumps, temperature increases in boilers, etc.

Reductions in potable water supply pressure occur whenever the amount of water being used exceeds the amount of water being supplied, such as during water line flushing, fire fighting, or breaks in water mains.

Backsiphonage is backflow caused by a negative pressure (i.e., a vacuum ~ or partial vacuum) in a Public water system or consumer’s potable water system.

The effect is similar to drinking water through a straw. Backsiphonage can occur when there is a stoppage of water supply due to nearby fire fighting, a break in a water main, etc.

Backflow into a public water system can pollute or contaminate the water in that system (i.e., backflow into a public water system can make the water in that system unusable or unsafe to drink), and each water supplier has a responsibility to provide water that is usable and safe to drink under all foreseeable circumstances.

Furthermore, consumers generally have absolute faith that water delivered to them through a public water system is always safe to drink. For these reasons, each water supplier must take reasonable precautions to protect its public water system against backflow.

Water suppliers usually do not have the authority or capability to repeatedly inspect every consumer’s premises for cross-connections and backflow protection. Alteratively, each water supplier should ensure that a proper backflow preventer is installed and maintained at the water service connection to each system or premises that poses a significant hazard to the public water system.

Generally, this would include the water service connection to each dedicated fire protection system or irrigation piping system and the water service connection to each of the following types of premises:

1. premises with an auxiliary or reclaimed water system:
2. industrial, medical, laboratory, marine or other facilities where objectionable substances are handled in a way that could cause pollution or contamination of the public water system;
3. premises exempt from the State Plumbing Code and premises where an internal backflow preventer required under the State Plumbing Code is not properly installed or maintained;
4. classified or restricted facilities; and
5. tall buildings.

Each water supplier should also ensure that a proper backflow preventer is installed and maintained at each water loading station owned or operated by the water supplier.

A backflow preventer is a means or mechanism to prevent backflow. The basic means of preventing backflow is an air gap, which either eliminates a cross-connection or provides a barrier to backflow. The basic mechanism for preventing backflow is a mechanical backflow preventer, which provides a physical barrier to backflow.

The principal types of mechanical backflow preventer are the reduced-pressure principle assembly, the pressure vacuum breaker assembly, and the double check valve assembly. A secondary type of mechanical backflow preventer is the residential dual check valve.

An RP is a mechanical backflow preventer that consists of two independently acting, spring-loaded check valves with a hydraulically operating, mechanically independent, spring-loaded pressure differential relief valve between the check valves and below the first check valve.

It includes shutoff valves at each end of the assembly and is equipped with test cocks. An RP is effective against backpressure backflow and backsiphonage and may be used to isolate health or non-health hazards.

A PVB is a mechanical backflow preventer that consists of an independently acting, spring-loaded check valve and an independently acting, spring-loaded, air inlet valve on the discharge side of the check valve. It includes shutoff valves at each end of the assembly and is eqipped with test cocks. A PVB may be used to isolate health or non-health hazards but is effective against backsiphonage only.

A DC is a mechanical backflow preventer that consists of two independently acting, spring-loaded check valves. It includes shutoff valves at each end of the assembly and is equipped with test cocks. A DC is effective against backpressure backflow and backsiphonage but should be used to isolate only non-health hazards.

Mechanical backflow preventers have internal seals, springs, and moving parts that are subject to fouling, wear, or fatigue. Also, mechanical backflow preventers and air gaps can be bypassed.

Therefore, all backflow preventers have to be tested periodically to ensure that they are functioning properly. A visual check of air gaps is sufficient, but mechanical backflow preventers have to be tested with properly calibrated gauge equipment.

Automatic fire sprinklers are individually heat-activated, and tied into a network of piping with water under pressure.

When the heat of a fire raises the sprinkler temperature to its operating point (usually 165ºF), a solder link will melt or a liquid-filled glass bulb will shatter to open that single sprinkler, releasing water directly over the source of the heat.

Electrical supervision of sprinkler systems to monitor valves and water flow is a major plus in assuring system reliability and effectiveness, and is required by many building codes for large and important system installations.

Absolutely not. It takes actual heat, usually 165ºF, to set off a sprinkler.

Only in the movies! Each sprinkler is independent and must be subjected to direct heat to go off.

The most important thing to do to keep your fire sprinkler in good shape is to have it inspected by a certified fire safety professional once a year.

Frequent fire sprinkler inspections will help catch any problems with your system. In addition, fire sprinkler system maintenance will usually lower insurance premiums.

While the exact number of fire extinguishers required for each building varies based on the unique layout and hazard level, as a general rule of thumb you should have no more than 75ft of space between Class A fire extinguishers and no more than 50ft between Class B fire extinguishers.

Every fire extinguisher has an alphanumeric rating that tells you what types of fires it can extinguish as well as the size of fire it can put out.
The letters stand for the class of fire the extinguisher can be used against:

• A - ordinary combustibles (wood, paper, plastic, etc.)
• B - flammable liquids (oil, gas, petroleum, etc.)
• C - electrical equipment
• D - metals
• K - cooking oils and fats

The numbers indicate how much of the fire can be put out by the fire extinguisher. Every number before the A means it is as effective as 1-1/4 gallons of water. For example, 2A means the fire extinguisher is as effective as 2-1/2 gallons of water, and so on. The numbers before B and C are a measure of the amount of square feet the fire extinguisher can put out. For example, a 10:BC fire extinguisher can extinguish a fire over 10 sq ft.