Front Load Single Sensor

INFICON Front Load Single crystal sensors offer proven reliability and durability and have the best thermal stability of any sensor head on the market. The front load design allows for easy insertion of the crystal holder in applications lacking sufficient room for side insertion.  Assembled mechanically rather than soldered, parts can be replaced conveniently in the field, if necessary. Sensors can be ordered individually or in a sensor / feedthrough combination that can be either welded or assembled with compression fittings.


  • Front load crystal holder
  • Easy installation
  • Available with 2.54 cm (1 inch) bolt feedthrough / CF40 Feedthrough
  • Adjustable length if ordererd with compression fittings
  • Sensor / Feedthrough combinations available welded to customer specified lengths
  • No brazing required if ordered with compression fittings or welded to feedthrough


Type Front Load Single Sensor
Maximum bakeout temp with no water 130° C
Maximum operating isothermal environment temperature with minimum water flow 400° C
SL-A _ _ _ _ Size (maximum envelope without shutter) 1.063 in. x 2.42 in. x 0.69 in. (27 mm x 61.47 mm x 17.53 mm)
SL-B_ _ _ _ Size (maximum envelope without shutter) 1.11 in. x 1.06 in. x 1.06 in. (28.19 mm x 26.92 mm x 26.92 mm)
Water tube 1/8 in. (3.175 mm) O.D. seamless stainless steel
Crystal exchange Front loading; self-contained package for ease of exchange
Mounting Two #4-40 tapped holes on the back of the sensor body
Installation Requirements  
Feedthrough 2 pass water 3/16 in. (4.8 mm) O.D. tubing with Microdot® coax connector
Other XIU or Oscillator to match specific controller, solenoid valve assembly 750-420-G1 for shuttered sensors
Water flow rate Minimum water flow 150-200 cc/min, 30° C max
Water quality Coolant should not contain chlorides as stress corrosion cracking may occur. Extremely dirty water may result in loss of cooling capacity.
Body and holder 304 type stainless steel
Springs, electrical contacts Au plated Be-Cu
Water tubes S-304, 0.125 in. (3.175 mm) O.D. x 0.015 in. (0.381 mm) wall thickness seamless stainless steel tubing
Connector (Microdot) Stainless steel, Teflon® and glass insulated
Insulators >99% Al2O3
Wire Teflon insulated copper
Braze Vacuum process high temperature Ni-Cr alloy
Crystal 0.550 in. (13.97 mm) Diameter
Feedthrough Specifications 1 in. bolt and Ultra-Torr (compression fitting) terminations:  
Materials 304 stainless steel, Teflon®, ceramic, beryllium nickel, VITON®
Temperature Operational environment to 300° C with water cooling or 165° C without
Mounting 1.015 in. ±0.010 in. diameter aperture
Feedthrough Specifications CF 40 (2 3/4 in. ConFlat) welded terminiations:  
Materials 304 stainless steel, Teflon, ceramic, beryllium nickel
Temperature Operational environment to 450° C with water cooling or 165° C without
Mounting Mates with 2 ¾ in. ConFlat type flanges with 1.375 in. I.D. min.
FL Single PN.png


Name Description
QCM Sensor Feedthroughs QCM Sensor Feedthroughs
Front Load Single Sensor
Part Number Description
750-420-G1 Solenoid Valve, 24V (for use with shuttered and multi-crystal sensors)


Name Description
Quartz Monitor Crystals Quartz Monitor Crystals

Spare Parts

Front Load Single Sensor
Part Number Description
007-007 Retainer spring (for crystal holder)
007-023 Ceramic Retainer
080-018 Set screw (for female coax)
082-044 Teflon screw (for leaf spring)
750-115-P4 Coupling (installs onto bellows assembly)
750-169-P2 Bellows assembly (coupling not included)
750-171-P1 Finger spring contact
750-172-G1 Crystal holder (includes retainer spring)
750-174-P2 Female coax
750-175-P1 Insulator (underneath leaf spring)
750-188-P3 Leaf Spring
750-210-G1 Shutter module (bellows assembly, shaft assembly, and shutter assembly)
750-215-G1 Shaft assembly (part of shutter module)
750-216-G1 Shutter assembly (part of shutter module)
In-vacuum cables
321-039-G12 In-vacuum cable, 15.2 cm (6 in.)
783-500-023 In-vacuum cable, 25.4 cm (10 in.)
007-252 In-vacuum cable, 30.5 cm (12 in.)
321-039-G11 In-vacuum cable, 61.0 cm (24 in.)
783-500-024 In-vacuum cable, 76.2 cm (30 in.)
007-044 In-vacuum cable, 78.1 cm (30.75 in.)
007-059 In-vacuum cable, 91.4 cm (36 in.)
007-061 In-vacuum cable, 121.9 cm (48 in.) - Requires ModeLock controller
321-039-G13 In-Vacuum Cable, 154.2 cm (60 in.) - Requires ModeLock controller
321-039-G14 In-vacuum cable, 182.9 cm (72 in.) - Requires ModeLock controller
321-039-G15 In-vacuum cable, 3.5 m (137.8 in.) - Requires ModeLock controller and 4 m XIU
321-039-G16 In-vacuum cable, 4 m (157.5 in.) - Requires ModeLock controller and 4 m XIU
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