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.

Aperture Dia.ThreadMax Operating Temp.Max Operating PressureHousing MaterialWindow MaterialMfg. P/N.Encole P/N.Price
0.380 inchNPT 3/8"65 C2170 psiAISI 316Quartz100671265A1000$275.99each
0.460 inchNPT 1/2"60 C2170 psiAISI 316Quartz100672265A1001RFQ
0.640 inchNPT 3/4"55 C2170 psiAISI 316Quartz100673265A1002RFQ
0.860 inchNPT 1"45 C2170 psiAISI 316Quartz100674265A1003$295.80each
1.180 inchNPT 1-1/4"40 C2170 psiAISI 316Quartz100675265A1004$368.87each
1.380 inchNPT 1-1/2"35 C2170 psiAISI 316Quartz100676265A1005$409.00each
1.800 inchNPT 2"35 C2170 psiAISI 316Quartz100677265A1006RFQ
0.350 inchNPT 3/8"65 C6170 psiAISI 316Quartz100765324A1000$308.36each
0.400 inchNPT 1/2"60 C6170 psiAISI 316Quartz100766324A1001$326.04each
0.550 inchNPT 3/4"55 C6170 psiAISI 316Quartz100767324A1002$387.35each
0.750 inchNPT 1"45 C6170 psiAISI 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.

Aperture Dia.ThreadMax Operating Temp.Max Operating PressureHousing MaterialWindow MaterialMfg. P/N.Encole P/N.Price
9.00 mmNPT 1/4"300 C100 barHastelloy C-22BorosilicateMet Type 61-025H406S05$287.54each
10.00 mmNPT 3/8"300 C100 barHastelloy C-22BorosilicateMet Type 61-038H406S06$333.95each
14.00 mmNPT 1/2"300 C100 barHastelloy C-22BorosilicateMet Type 61-050H406S07$378.50each
18.00 mmNPT 3/4"300 C100 barHastelloy C-22BorosilicateMet Type 61-075H406S09$435.90each
22.00 mmNPT 1"300 C100 barHastelloy C-22BorosilicateMet Type 61-100H406S11$540.00each
25.00 mmNPT 1-1/4"300 C100 barHastelloy C-22BorosilicateMet Type 61-125H406S12$622.00each
30.00 mmNPT 1-1/2"300 C100 barHastelloy C-22BorosilicateMet Type 61-150H406S13$712.00each
37.00 mmNPT 2"300 C100 barHastelloy C-22BorosilicateMet Type 61-200H406S14$1370.00each
55.00 mmNPT 3"300 C100 barHastelloy C-22BorosilicateMet Type 61-300H406S16$2321.00each
9.00 mmNPT 1/4"280 C100 bar2205 DuplexBorosilicateMet Type 61-025S405S05$181.27each
10.00 mmNPT 3/8"280 C100 bar2205 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.

Aperture Dia.ThreadMax Operating Temp.Max Operating PressureHousing MaterialWindow MaterialMfg. P/N.Encole P/N.Price
5.00 mmNPT 1/4"150 C100 bar2205 DuplexSoda limeMet 62-025S410S05$214.08each
7.00 mmNPT 3/8"150 C100 bar2205 DuplexSoda limeMet 62-038S410S06$231.05each
11.00 mmNPT 1/2"150 C100 bar2205 DuplexSoda limeMet 62-05S410S07$248.12each
17.00 mmNPT 3/4"150 C100 bar2205 DuplexSoda limeMet 62-075S410S09$262.12each
19.00 mmNPT 1"150 C100 bar2205 DuplexSoda limeMet 62-100S410S11$283.15each
22.00 mmNPT 1-1/4"150 C100 bar2205 DuplexSoda limeMet 62-125S410S12$288.05each
25.00 mmNPT 1-1/2"150 C100 bar2205 DuplexSoda limeMet 62-150S410S13$299.25each
35.00 mmNPT 2"150 C100 bar2205 DuplexSoda limeMet 62-200S410S14$381.23each
5.00 mmNPTF 1/4"150 C100 bar2205 DuplexSoda limeMet 62F-025S413S05$214.80each
7.00 mmNPTF 3/8"150 C100 bar2205 DuplexSoda limeMet 62F-038S413S06$231.09each
11.00 mmNPTF 1/2"150 C100 bar2205 DuplexSoda limeMet 62F-050S413S07$249.15each
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Oil-Rite Corporation

Low Cost Fused NPT-Threaded Sight Glasses, Zinc-Plated Carbon Steel. From $6.00

Sodalime glass is fused to a plain carbon steel body which is Zinc-plated for added corrosion resistance. These sight glasses can be threaded directly into a pipe, or a boss welded to a pipe with subsequent threads cut into the boss. These are ideal budget sight glasses/viewports for visual observation of liquid levels and their colors. Applications include hydraulic systems with mineral oils, diesel, and other common petrochemicals where low cost is required. Not suitable for cycling high temperature, high pressure or aggressively corrosive applications.

Aperture Dia.ThreadMax Operating Temp.Max Operating PressureHousing MaterialWindow MaterialMfg. P/N.Encole P/N.Price
0.340 inchNPT 1/4"130 F125 psiCarbon Steel, PlatedSoda limeA2890-1OR110001$6.62each
0.560 inchNPT 1/2"130 F125 psiCarbon Steel, PlatedSoda limeA2890-3OR110003$7.46each
0.940 inchNPT 1"130 F125 psiCarbon Steel, PlatedSoda limeA2890-5OR110005$12.26each
1.190 inchNPT 1-1/4"130 F125 psiCarbon Steel, PlatedSoda limeA2890-6OR110006$21.91each
1.440 inchNPT 1-1/2"130 F125 psiCarbon Steel, PlatedSoda limeA2890-7OR110007$25.98each
1.880 inchNPT 2"130 F125 psiCarbon Steel, PlatedSoda limeA2890-8OR110008$31.49each
0.440 inchNPTF 3/8"130 F125 psiCarbon Steel, PlatedSoda limeA2890-2OR110002$6.79each
0.750 inchNPTF 3/4"130 F125 psiCarbon Steel, PlatedSoda limeA2890-4OR110004$9.57each
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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