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Product Listing

Gate Valves
SEMI / MESC Rectangular - Introduction

SEMI short for ‘Semiconductor Equipment & Materials International’ developed the ‘Modular Equipment Standards Committee’, better known as MESC, to establish global interchangeability and modularity between products from the numerous sources in the semiconductor manufacturing equipment and components industry.

MDC LVHC series rectangular gate valves meet or exceed all applicable MESC standards. LVHC valves incorporate a patented one piece gate and carriage design that virtually eliminates vibration and particle generation. O-ring scuffing and wear are non-existent because of a floating driver bar design. The one piece gate and carriage can be removed through the valve’s bonnet flange for gate seal replacement, cleaning, etc., without disassembling the valve body from the system.

Del-Seal™  CF Flanges

LVHC valves are available in either 2.75" (70mm) or 1.97" (50mm) flange-to-flange thicknesses, with rectangular ports of 1.25 x 8.75" (32 x 222mm) or 1.81 x 9.30" (46 x 236mm) dimensions. These valves are designed for use in high vacuum load-lock systems used in semiconductor processing, where low vibration and low particle generation are imperative. The valves’ low outgassing characteristics can be attributed to a fusion welded 300 series stainless steel body, welded AM-350 stainless steel nesting bellows as well as small cross section O-rings and the elimination of blind internal cavities. Custom design valves are available on request.

Pneumatic actuators are fitted with mechanical position indicators which indicate fully open and fully closed positions. This MPI system consists of two single pole, double throw micro switches fitted with integral hinged lever and roller actuators. Each micro switch is wired in a normally open position via a seven pin circular threaded connector. Mating female cable connectors are included.

Normally closed switch wiring is available on request. Precise positioning of micro switches is made possible by a patented vernier adjustment mechanism only available on MDC gate valves.

Pneumatic actuators are equipped with dual impulse Herion 24 VDC air control solenoid valves. All solenoid valves are fitted with DIN type connectors that conform to international standards. DIN connectors provide simplicity, convenience and fast, easy electrical installation. Solenoid valves are designed for use with compressed air from 0 to 125psig. Air should be clean and uncontaminated. When in doubt, install a filter with filtering capacity of 40 microns. Periodically remove and clean or replace filter element.


  • Viton® O-Ring Sealed Gates
  • Stainless Steel Construction
  • Electropneumatic Operation
  • Mechanical Position Indicator
  • Patented Uni-Loc™ Locking Mechanism
  • Double Impulse 24VDC Air Control Solenoid

Additional Features

  • SEMI / MESC port flanges for use with claw type fasteners
  • 1.25 x 8.75" (32 x 222mm) and 1.81 x 9.30" (46 x 236mm) inch rectangular port apertures
  • 2.75" ( 70mm) or 1.97" (50mm) flange-to-flange body thickness
  • Viton® elastomer bonnet and gate seals
  • Welded bellows actuator seal
  • TIG welded internal body joints
  • Electropolished interior and exterior surfaces
  • Low vibration and particle generation
  • Dry film lubricated bearings

For product listing, features and specifications click on links below
 SEMI / MESC High Vacuum Series

 Related Topics
 C-Loc® Rectangular - Introduction
 Rectangular Gate Valve Specifications and Products
 Circular Gate Valve Specifications and Products
 Gate Valves - Introduction