NPT Sight Glass

NPT sight glasses are typical NPT fittings having NPT male threads, where the window is encased into the metal housing forming a single-piece part.

Designed up to 7000 psi pressure, these sight glasses have optical clarity suitable for imaging systems and also for looking at oil levels inside pressure vessels, or checking the color of a refrigerant. These NPT sight glasses transmit a broad spectrum of wavelengths, ranging from near-infrared, visible light, to ultraviolet. Sight glasses with quartz use material GE-124 quartz. It's a pure form of silica commonly used in semiconductor equipment. This quartz has high purity for use in a process in semiconductor reactors.

Encole

NPT-Threaded High Pressure Sight Glasses with Quartz Windows, 316 Stainless Housing

Sight window with NPT threads conforming to ASME B1.20.1. For visual inspection, machine vision, laser sensors, in use with all common hydraulic oils, refrigerants, pharmaceutical processing equipment, paper & pulp plants, marine exterior, oil wells, feedwater heaters. Resists most oxidizing acids and salt sprays. Ideal choice for applications requiring no compromises in optical clarity. The window is flat on both sides, and precisely polished to surface quality of 40-20 S-D per MIL-O-13830. Because the window material is quartz, this sight glass can be used in applications requiring extended transmission ranges. Specifically, this window transmits over 50 percent of light from 217 to 3600 nm wavelengths. Quartz window is sealed into the housing with non-outgassing quartz-filled bond forming a single-piece part. This sight glass has a long working life under severe temperature swings and prolonged exposures to UV light.

ThreadAperture Dia.Max Operating PressureMax Operating Temp.Housing MaterialWindow MaterialMfg. P/N.Encole P/N.Price
NPT 3/8"0.380 inch2170 psi65 CAISI 316Quartz100671265A1000$275.99each
NPT 1/2"0.460 inch2170 psi60 CAISI 316Quartz100672265A1001RFQ
NPT 3/4"0.640 inch2170 psi55 CAISI 316Quartz100673265A1002$289.16each
NPT 1"0.860 inch2170 psi45 CAISI 316Quartz100674265A1003$295.80each
NPT 1-1/4"1.180 inch2170 psi40 CAISI 316Quartz100675265A1004$368.87each
NPT 1-1/2"1.380 inch2170 psi35 CAISI 316Quartz100676265A1005$409.00each
NPT 2"1.800 inch2170 psi35 CAISI 316Quartz100677265A1006RFQ
NPT 3/8"0.350 inch6170 psi65 CAISI 316Quartz100765324A1000$308.36each
NPT 1/2"0.400 inch6170 psi60 CAISI 316Quartz100766324A1001$326.04each
NPT 3/4"0.550 inch6170 psi55 CAISI 316Quartz100767324A1002$387.35each
NPT 1"0.750 inch6170 psi45 CAISI 316Quartz100768324A1003$404.68each
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Metaglas, Herberts Industrieglas GmbH & Co. KG

NPT-Threaded Fused Sight Glasses, Borosilicate Windows

Fusing glass to metal creates a strong, hermetically sealed single-piece part. The advantage of this construction is high strength of the glass, which ensures safety of operation, even during cycling operating temperatures common with equipment starts and stops. The part is easy to install and has a long working life without maintenance. These sight window have NPT threads conforming to ASME B1.20.1. For use with all common hydraulic oils, refrigeration, water heaters, and compressed air applications. Note: The image of the objects behind the glass may be distorted as the glass is slightly concave. For perfect optical clarity choose sight glasses with glass filling the entire height of the housing, where both sides of the glass are flat.

ThreadAperture Dia.Max Operating PressureMax Operating Temp.Housing MaterialWindow MaterialMfg. P/N.Encole P/N.Price
NPT 1/4"9.00 mm100 bar300 CHastelloy C-22BorosilicateMet Type 61-025H406S05$287.54each
NPT 3/8"10.00 mm100 bar300 CHastelloy C-22BorosilicateMet Type 61-038H406S06$333.95each
NPT 1/2"14.00 mm100 bar300 CHastelloy C-22BorosilicateMet Type 61-050H406S07$378.50each
NPT 3/4"18.00 mm100 bar300 CHastelloy C-22BorosilicateMet Type 61-075H406S09$435.90each
NPT 1"22.00 mm100 bar300 CHastelloy C-22BorosilicateMet Type 61-100H406S11$540.00each
NPT 1-1/4"25.00 mm100 bar300 CHastelloy C-22BorosilicateMet Type 61-125H406S12$622.00each
NPT 1-1/2"30.00 mm100 bar300 CHastelloy C-22BorosilicateMet Type 61-150H406S13$712.00each
NPT 2"37.00 mm100 bar300 CHastelloy C-22BorosilicateMet Type 61-200H406S14$1370.00each
NPT 3"55.00 mm100 bar300 CHastelloy C-22BorosilicateMet Type 61-300H406S16$2321.00each
NPT 1/4"9.00 mm100 bar280 C2205 DuplexBorosilicateMet Type 61-025S405S05$181.27each
NPT 3/8"10.00 mm100 bar280 C2205 DuplexBorosilicateMet Type 61-038S405S06$189.55each
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Metaglas, Herberts Industrieglas GmbH & Co. KG

Fused NPT Sight Glasses, Duplex Steel 2205, Sodalime, Full Glass Height

Soda lime glass is fused to a duplex steel 2205 housing, where the glass extends the entire height of the fitting. Glass is flush with both ends of the housing. Sides of the glass are flat and lapped to approximately S-D: 80-40, an optical finish of a typical room window. This optical clarity is suitable for undistorted viewing though the sight glass. For visual inspection, machine vision, optical sensors, in use with all common hydraulic oils, refrigeration, water heaters, and compressed air applications. Connections are NPT or NPTF (Dryseal) threads conforming to ASME B1.20.1.

ThreadAperture Dia.Max Operating PressureMax Operating Temp.Housing MaterialWindow MaterialMfg. P/N.Encole P/N.Price
NPT 1/4"5.00 mm100 bar150 C2205 DuplexSoda limeMet 62-025S410S05$214.08each
NPT 3/8"7.00 mm100 bar150 C2205 DuplexSoda limeMet 62-038S410S06$231.05each
NPT 1/2"11.00 mm100 bar150 C2205 DuplexSoda limeMet 62-05S410S07$248.12each
NPT 3/4"17.00 mm100 bar150 C2205 DuplexSoda limeMet 62-075S410S09$262.12each
NPT 1"19.00 mm100 bar150 C2205 DuplexSoda limeMet 62-100S410S11$283.15each
NPT 1-1/4"22.00 mm100 bar150 C2205 DuplexSoda limeMet 62-125S410S12$288.05each
NPT 1-1/2"25.00 mm100 bar150 C2205 DuplexSoda limeMet 62-150S410S13$299.25each
NPT 2"35.00 mm100 bar150 C2205 DuplexSoda limeMet 62-200S410S14$381.23each
NPTF 1/4"5.00 mm100 bar150 C2205 DuplexSoda limeMet 62F-025S413S05$214.80each
NPTF 3/8"7.00 mm100 bar150 C2205 DuplexSoda limeMet 62F-038S413S06$231.09each
NPTF 1/2"11.00 mm100 bar150 C2205 DuplexSoda limeMet 62F-050S413S07$249.15each
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This is the full technical specification: http://quartz.com/gedata.html UV cutoff is at < 160 nm. Encole also manufactures custom sight glasses with higher optical properties, using Suprasil 311 or Corning 7980.
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