Anti hammer three function air valve for sewage Mod. SCA 2" - PN 16

The air valve guarantees the proper  operation of sewage  lines allowing the entrance of  large quantities of air in case of pipe burst or draining phases, the release of air pockets during working conditions and the controlled air outflow speed.


Construction and advantages

  • Lower body designed  with strongly  sloped high walls to avoid grease  and/or  other material deposit, and it contains four ribs to guide the stainless steel float.
  • Upper body containing the AS and the air release mechanism which is protected against water hammer effect , during rapid filling phases,  by a s.s. diffuser.
  • Mobile block including a large AISI 316 stainless steel float,  placed  on the lower  body and connected through a stainless steel  rod to the air release mechanism.
  • Anti Shock  automatism composed of a metallic disk with 2 or more small orifices,  a guide bar and a counteracting spring in stainless steel.
  • Drainage valve for chamber control and draining.
  • Maintenance can be easily performed from the top without removing  the air valve from the pipe.
  • Evacuation bend  suitable for flooded environments with 1" threaded outlet.


Operating principle

  1. Entrance of large volumes of air
    During pipeline  draining  or bursting  phases it is necessary to bring  in as much  air as the quantity of out-flowing water to avoid vacuum conditions.
  2. Controlled air discharge
    The SCA air valve is provided  with a mechanism called AS. During vacuum conditions the mobile block is laid over the diffuser, the antishock disk comes down pulling the stainless steel spring  and allows the entrance of  large volumes of air through the main orifice  to compensate the vacuum effect.
  3. Air release during working conditions.
    During operation, an air pocket  is accumulated in the upper  part of the valve s body, little by little it is compressed and its pressure arrives  to water pressure, its volume increases pushing the water downwards. Following Archimede s principle the float, no longer sustained by water thrust,  will drop freeing the nozzle hole helping the release of the air pocket,  while the upper  disk closes the main orifice due to internal pressure.

For air flow performance of SCA 2" please refer to the chart depicted on the next page.


Working conditions
Waste water 70°/158
°F Max; Maximum pressure 16 bar/ 232 psi;
Minimum pressure 0,35 bar/ 5.1 psi.

Technical features
Lower body, upper body and cover entirely made in ductile cast iron GJS  500-7,  internal  and  external painted with epoxy  powder applied  using fluidized  bed technology.
Obturator in polypropylene
Nozzle and  gasket holder in stainless steel A S  316
AS  guide bar  and  spring in stainless steel
AS disk  in brass
Float and  rod  in stainless steel A S  316
Gaskets in NBR
Sealing seat in stainless steel A S  304
Drainage valve in galvanized brass  or stainless steel