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Water Hammer Arresters Frequently Asked Questions

  1. Will water hammer arresters control the movement in piping mains?
    The movement in piping mains is caused by shock and partially by the flow of water through the mains. The greatest movement is caused by shock which can be controlled by the installation of water hammer arresters. The movement caused by water flow can be controlled by the proper placement of pipe hangers and supports.

  2. Is it possible to control the shock created by pumping equipment?
    When a pump shuts off, some degree of shock will be experienced in the discharge line. This is caused by the back surge of water to the pumping equipment. The shock can be controlled in most applications by the installations of a properly sized water hammer arrester. The unit should be installed at a tee connection in the vertical discharge line.

  3. Will a water hammer arrester prevent check valve slam?
    A  water hammer arrester will absorb the shock and minimize the slam noise. A soft seat in the check valve will then assure a quiet closure.
  4. Is the shock generated in dishwasher piping controllable?
    A solenoid or other type of quick closure valve is employed for dishwasher applications. A properly sized water hammer arrester installed on the pressure side of the solenoid valve will eliminate the shock and noise.

  5. Is the shock generated in home washing machines controllable?
    Yes, a properly sized water hammer arrester placed on the cold and hot water supplies to the washing machine will absorb the shock as caused by quick closure devices.

  6. Will water hammer arresters control the shock experienced in commercial laundry machines?
    A violent shock is created in commercial laundry piping as a result of quick closure valves. The 5060 Hydrotrol has been designed for severe applications such as this. However, at times is not large enough to effectively control the situation and another method must be utilized. These applications shall be submitted with all pertinent data to Smith’s Sales Engineering for evaluation.

  7. Can shock be prevented in other types of liquid conveying systems?
    The 5005-5050 stainless steel bellows units can be used with most types of liquid conveyed in a piping distribution system. Therefore, if a shock is encountered, it can be controlled. When liquids other than water are involved, it is recommended that Smith’s Sales Engineering group be consulted for evaluation.

  8. Will water hammer arresters eliminate piping vibration?
    If the vibration is caused by the occurrence of shock in the piping system it can be avoided if a properly sized water hammer arrester is installed near the quick closure valve.

  9. Are water hammer arresters required in the average residence?
    Yes, a severe shock can occur in the residential piping system, especially when excessive water pressures are involved. Most of the premature failures of piping, hot water storage heaters, home laundry machines, automatic control valves and flush tanks or valves, may be attributed to shock caused by quick closure valves. Properly sized water hammer arresters should be installed on the hot and cold water supply piping to that fixture, equipment or apparatus wherein shock can be produced. A pressure reducing valve installed on the discharge side of the water meter can be most helpful in protecting the residential piping system.

  10. Will water hammer arresters rectify every shock condition?
    Occasionally, a piping system is improperly designed or installed. Therefore, it is necessary to correct the installation before you can cure the shock. After this has been accomplished a properly sized water hammer arrester will rectify the shock condition.

  11. What is the importance of cubic inch displacement in water hammer arresters?
    A prescribed amount of cubic inch displacement is required for each type of device intended for the control of shock. Since the Hydrotrols are pressurized, its displacement volume is not actually utilized until the water pressure exceeds 60 P.S.I. By comparison, the air chamber type device require a displacement volume approximately six times that of each Hydrotrol unit.

  12. Do Water Hammer Arresters require access panels?
    The ‘all stainless steel’ constructed units with internal stainless steel bellows are guaranteed for the life of the piping system. Because of their construction, longevity and years of successful operation, we are comfortable with stating that no access is required. The piston type unit should be accessible or be provided with an access panel. Piston units have moving parts sealed by an o-ring which means at some time in the future, replacements or maintenance will be required. Although some piston units have life time guarantees and have no access panel requirement, at some point access will be required or they will be left as is in a failed state.

  13. Can a Water Hammer Arrester be placed at the top of a riser and be effective?
    No. The location of the unit itself is essential for proper operation and effectiveness. Usually, the top of the riser is so remote to the source of the problem, the unit never has an opportunity to perform its job. The location should be at the piping serving the fixture(s) and normally between the last two fixtures. Refer to the Smith ‘Yellow Pages’ catalog, Water Hammer Arrester section for complete information on sizing, placement and selection. The Plumbing & Drainage Institute (PDI) Water Hammer Arrester Standard, WH-201, may also be referred to for sizing, placement and selection.