Guidelines for Vacuum Breaker Installation, Operation and Maintenance
Maximum Pressure: 125 PSI
Maximum Temperature: 180°F
ASSE Certified under ASSE Standard 1001
Atmospheric vacuum breakers are used to prevent back-siphonage of contaminated water into a potable water system. They are not designed to protect against backpressure conditions; protection against backpressure may require installation of a backflow preventer in the water supply line.
WaterSaver vacuum breakers are intended for use on laboratory faucets and valves. They are typically installed as an integral part of a laboratory faucet gooseneck. In addition, they are used in water supply systems installed in fume hoods, mounted between a remote control water valve and an outlet fitting. As such, WaterSaver vacuum breakers are designed and constructed specifically for the requirements of laboratory applications. They are designed to seal properly and prevent spillage at as low a flow as possible, thus facilitating many common laboratory procedures. However, under certain circumstances, spillage of water from under the vacuum breaker cover can occur.
The purpose of these guidelines is to assist in the correct installation, operation and maintenance of WaterSaver vacuum breakers. In addition, these guidelines will assist in troubleshooting in the event that spillage does occur.
IMPORTANT: Be sure to review applicable local plumbing codes prior to selecting or installing a vacuum breaker. Many codes have specific provisions regarding the type of vacuum breaker that may be used and the design of the system in which it is used.
The water supply line must be thoroughly flushed prior to installation. The presence of any scale, debris, chips, thread sealant, etc. in the water line may cause fouling of the vacuum breaker, prevent proper sealing of the float cup and damage internal components.
The vacuum breaker must be installed with the supply connected to the bottom inlet of the vacuum breaker.
An atmospheric vacuum breaker must be installed downstream of the last valve in the water supply line.
The Uniform Plumbing Code requires that "potable water outlets with hose attachments...shall be protected by... an atmospheric vacuum breaker installed at least six (6) inches above the highest point of usage and located on the discharge side of the last valve." [Uniform Plumbing Code, Section 603.4.7 (2003)] Consequently, when the vacuum breaker is installed, the bottom of the vacuum breaker body must be at least 6" above the flood level rim of the sink or fixture into which water is discharged. [See Figure 1.] Where a hose is to be attached to a serrated hose end, the vacuum breaker must be installed at least 6" above the highest point to which the hose can be raised. [See Figure 1.]
Vacuum breakers must be installed in a plumb and level position, perpendicular to the finished floor. If a vacuum breaker is installed in a tilted or angled position, the float cup will tend not to seal squarely against the bottom of the vacuum breaker bonnet. This can promote leakage under low flow conditions.
Since atmospheric vacuum breakers require routine inspection and maintenance (primarily cleaning and/or replacement of internal components), they should be installed in locations in which they are readily accessible. In addition, the Uniform Plumbing Code prohibits installing a backflow preventer in any area containing toxic, poisonous or corrosive fumes. [Uniform Plumbing Code, Section 603.4.15 (2003)] Vacuum breakers should thus not be installed within the work space of a laboratory fume hood.
When the water control valve is closed, the vacuum breaker float cup rests on the vacuum breaker seat. [See Figure 2.] In this position, the atmospheric vent is open and the waterway through the seat is closed.
When the water valve is opened, the water flow pushes the float cup up off the seat and against the vacuum breaker bonnet. The float cup gasket seals against the bottom face of the bonnet. This seal prevents water from passing through the atmospheric vent and spilling out from underneath the vacuum breaker cover.
In the event of a loss of pressure on the upstream side of the vacuum breaker and the resulting creation of a negative pressure in the supply line, the float cup drops back down onto the seat. This opens the atmospheric vent and closes the waterway. This action admits air into the discharge line downstream of the vacuum breaker, thereby preventing the creation of a vacuum and stopping any back-siphonage.
An atmospheric vacuum breaker cannot be used in applications where it is subject to continuous water pressure. In addition, the water control valve should not be left open for extended periods of time.
The most common problem associated with atmospheric vacuum breakers is the occurrence of spillage of water from underneath the vacuum breaker cover. There are many possible causes of this. Set forth below is a list of the potential causes of spillage, together with the appropriate solution for the problem:
- Vacuum Breaker Installed At Angle. As noted above, if a vacuum breaker is installed in a tilted or angled position, the float cup will not seal evenly against the bottom of the bonnet. To address this issue, adjust the position of the vacuum breaker so as to be plumb and level.
- Contamination of Float Cup Gasket. If the water contains a high level of calcium or other minerals, deposits and scale can accumulate on the float cup gasket. If this occurs, the gasket will not seal completely against the bonnet. The gasket should be cleaned or replaced.
- Contamination of Bonnet. Build-up of deposits can occur on the seating surface of the bonnet as well. The bonnet must then be cleaned or replaced.
- High Water Pressure. As noted above, WaterSaver vacuum breakers are designed specifically for laboratory applications. The float cup and gasket are extremely light to permit sealing at as low a flow as possible (since many laboratory procedures require low flow over an extended period of time). When used in water systems with high water pressure (greater than 70 PSI), these components can wear out more quickly than at low pressure. If that occurs, the vacuum breaker may not seal properly at low flow. In higher pressure applications, the float cup and gasket might require replacement at more frequent intervals.
- Deterioration of Bonnet Gasket. The vacuum breaker bonnet is sealed into the vacuum breaker body using a nylon gasket or O-ring. Over time, this gasket or O-ring can deteriorate and leakage can occur. In that event, the gasket or O-ring should be replaced.
- Connection to Elevated Equipment. As noted above, the vacuum breaker must be installed at least 6" above the flood level rim of the sink or the highest point which can be reached by a hose attached to the outlet. Thus, if a hose is attached to the serrated end of a laboratory faucet, the free end of the hose should not be capable of reaching a height that is less than 6" below the vacuum breaker.
Spillage can occur in the event that a hose is attached to a faucet and extended above the level of the vacuum breaker. In this situation, when the valve is opened and water is flowing through the system, there can be an accumulation of water in the hose downstream of the vacuum breaker. The pressure created by the weight of the downstream water may exceed the water pressure upstream of the vacuum breaker, causing a negative pressure situation. This will cause a reversal of flow, the vacuum breaker will close, and spillage will occur. In this situation, the vacuum breaker is acting exactly as it is designed in preventing backflow.
The situation described above is most likely to occur when the water control valve is opened a slight amount and left in this position for a long period of time. Fluctuations in supply line pressure and flow may cause the float cup to "flutter" rather than seal continuously against the bonnet. This will accentuate the tendency for a negative pressure situation to develop.
One possible solution for spillage of this type is to install a non-positive closing volume control device (such as the WaterSaver BO358) on the faucet outlet. The control valve can then be fully opened, permitting the vacuum breaker float cup to seal. Water flow is metered using the volume control on the outlet. As noted above, the Uniform Plumbing Code requires that vacuum breakers be located on the discharge side of the last valve in the water line. Therefore, the volume control device must not be capable of fully closing.