Parallel Slide Isolating Gate Valves are particularly suitable for applications
where high pressure, high temperature steam or water are involved, as in power generation and process applications.

Popular Manufacturers:


Parallel Slide Valves


  • Hopkinsons
  • Taylor
  • Shaw
  • Bailey




Leak Rates for Valves


All valves are designed to meet a designated internal permissible leak rate standard (FCI/ANSI).  There are six (6) permissible leak rates or Classes numbered 1 through VI. The higher the leak rate number, the lower permissible internal leak rate.


  • Class I valve, will the highest internal leak rate and usually the lowest cost.
  • Class VI valve will have the lowest permissible internal leak rate therefore cost will increase.


Identifying the permissible internal leak rate for a valve has to be one of the top priorities when choosing the correct valve.  A valve with a high leak rate, will cause excessive wear. The valves with a high leak rate will internally pass more medium and result in premature valve failure.


There are six different seat leakage classifications as defined by ANSI FCI 70-2.


  • CLASS I: is also known as dust tight and can refer to metal or resilient seated valves.
  • CLASS IV: is also known as metal to metal. It is the kind of leakage rate you can expect from a valve with a metal shut-off disc and metal seat.
  • CLASS Vl: is known as a soft seat classification. Soft Seat Valves are those where the seat or shut-off disc or both are made from some kind of resilient material such as Teflon

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