Model KM 9902.1 117 (Z35) - Vertical Lift Type Check Valves with Branch Piece
Flanged vertical lift-type check valve with branch piece type KM 9902.1 117 (Z 35) is designed to protect pumps against reverse flow of the pumped fluid or no-load running. If the pressure of the fluid in the piping system behind the pump exceeds the value of the pressure generated by the pump and the fluid starts flowing back, the disc closes the check valve automatically. The pumped fluid is then discharged through the branch piece to the discharge pipe which mouths into the pump tank.
Vertical lift-type check valves are not designed as conventional isolating valves. If permanent tightness of the disc is required, an isolating valve shall be installed into the delivery piping. The service fluid shall not contain hard and abrasive particles as this could damage the seating surfaces and bring about heavier untightness or sticking of the disc in the bearings. The same applies to impurities in the piping system during installations, repairs or replacements.
The check valves are designed to be used with fluids in groups 1and 2 according to Section 3(1)(a, b) of Decree of the Government No. 26/2003 as subsequently amended, i.e. water with the exception of potable water, non-aggressive fluids (liquids, gases, vapours, air), oil and oil products, gaseous fuels, inorganic and organic media (acc. to materials used and after an agreement with a manufacturer). This specification corresponds to Article 9 (2.1, 2.2) of the European Parliament and Council Directive 97/23/EC. The resistance of the check valve to the fluid and its temperature is limited by the chemical composition of the check valve materials. It is therefore recommended to consult the suitability for the relevant fluid with the manufacturer. Allowable service pressures are in compliance with the pressure-temperature ratings.
The main part of the flanged vertical lift-type check valve with branch piece is a one-piece body which is made of rolled or forged steel. The body contains an inlet disc guide and an outlet disc guide with plain bearings which are pressed into the body. The pressed-in parts are secured by centre punching or welds. The disc guides are secured in place by the counter-flanges of the piping. The seats of both the body and the disc are usually weld-deposited with austenitic steel of 18/8 CrNi type or Stellite 6 – type of the weld overlay depends on the material composition of the check valve. The disc is lapped with the body seat. The branch piece is attached to the body by welding.
Connection to piping
Overall dimensions are shown in the datasheet. Dimensions according to standards:
- connection according to EN 1092–1
- face-to-face dimensions in pressure classes PN 16, 25, 40 – Series 1 according to EN 558–1
- face-to-face dimensions in pressure classes PN 63, 100, 160 – Series 2 according to EN 558–1
- face-to-face dimensions in pressure classes PN 250, 320, 400 – not standardized
According to EN 12 266–1 as a standard, i.e. shell strength test P10, P11, seat tightness test P12 (water pressure 1,1×PN and air pressure 0,6 MPa), leakage rate A – zero leakage, operability test F20. Standard ČSN EN 13709 specifies that a seat leakage corresponding to leakage rate C according to ČSN EN 12266–1 is allowed in case of test P12. If required by the Customer, additional tests may be performed as well.
Installation, service and maintenance
Vertical lift-type check valve shall be installed in vertical position. As it is a uni-directional valve, the fluid flow shall correspond to the arrow marked on the valve body. When installing the vertical lift-type check valve to piping it should be taken into account the fact that that in the fully open position of the valve the shaft of cone protrudes above the outlet flange by a distance which is equal to the maximum cone lift.
The valve requires no special maintenance or adjustment. If the values of temperature and pressure of the fluid and quantity of the fluid flowing through the branch piece as specified on the valve label are adhered to, the check valve operation is fully automatic.