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 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.

NPT-Threaded 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. Max Operating Pressure Max Operating Temp. Housing Material Thread Window Material Encole Part Number Price
0.380 inch 2170 psi 140 C AISI 316 NPT 3/8" Quartz 265A1000 $244.95 each
0.460 inch 2170 psi 130 C AISI 316 NPT 1/2" Quartz 265A1001 $255.78 each
0.640 inch 2170 psi 120 C AISI 316 NPT 3/4" Quartz 265A1002 $259.80 each
0.860 inch 2170 psi 110 C AISI 316 NPT 1" Quartz 265A1003 $275.99 each
1.180 inch 2170 psi 105 C AISI 316 NPT 1-1/4" Quartz 265A1004 $368.87 each
1.380 inch 2170 psi 90 C AISI 316 NPT 1-1/2" Quartz 265A1005 $409.00 each
1.800 inch 2170 psi 85 C AISI 316 NPT 2" Quartz 265A1006 $498.16 each
0.350 inch 6170 psi 140 C AISI 316 NPT 3/8" Quartz 324A1000 $308.36 each
0.400 inch 6170 psi 130 C AISI 316 NPT 1/2" Quartz 324A1001 $326.04 each
0.550 inch 6170 psi 120 C AISI 316 NPT 3/4" Quartz 324A1002 $341.93 each
0.750 inch 6170 psi 110 C AISI 316 NPT 1" Quartz 324A1003 $354.68 each
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NPT-Threaded Fused Sight Glasses, Duplex Steel, Hastelloy Housings, 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. Max Operating Pressure Max Operating Temp. Housing Material Thread Window Material Encole Part Number Price
9.00 mm 100 bar 300 C Hastelloy C-22 NPT 1/4" Borosilicate 406S05 $287.54 each
10.00 mm 100 bar 300 C Hastelloy C-22 NPT 3/8" Borosilicate 406S06 $333.95 each
14.00 mm 100 bar 300 C Hastelloy C-22 NPT 1/2" Borosilicate 406S07 $378.50 each
18.00 mm 100 bar 300 C Hastelloy C-22 NPT 3/4" Borosilicate 406S09 $435.90 each
22.00 mm 100 bar 300 C Hastelloy C-22 NPT 1" Borosilicate 406S11 $540.00 each
25.00 mm 100 bar 300 C Hastelloy C-22 NPT 1-1/4" Borosilicate 406S12 $622.00 each
30.00 mm 100 bar 300 C Hastelloy C-22 NPT 1-1/2" Borosilicate 406S13 $712.00 each
37.00 mm 100 bar 300 C Hastelloy C-22 NPT 2" Borosilicate 406S14 $1,370.00 each
55.00 mm 100 bar 300 C Hastelloy C-22 NPT 3" Borosilicate 406S16 $2,321.00 each
9.00 mm 100 bar 280 C 2205 Duplex NPT 1/4" Borosilicate 405S05 $181.27 each
10.00 mm 100 bar 280 C 2205 Duplex NPT 3/8" Borosilicate 405S06 $189.55 each
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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. Max Operating Pressure Max Operating Temp. Housing Material Thread Window Material Encole Part Number Price
5.00 mm 100 bar 150 C 2205 Duplex NPT 1/4" Soda lime 410S05 $214.08 each
7.00 mm 100 bar 150 C 2205 Duplex NPT 3/8" Soda lime 410S06 $231.05 each
11.00 mm 100 bar 150 C 2205 Duplex NPT 1/2" Soda lime 410S07 $248.12 each
17.00 mm 100 bar 150 C 2205 Duplex NPT 3/4" Soda lime 410S09 $262.12 each
19.00 mm 100 bar 150 C 2205 Duplex NPT 1" Soda lime 410S11 $283.15 each
22.00 mm 100 bar 150 C 2205 Duplex NPT 1-1/4" Soda lime 410S12 $288.05 each
25.00 mm 100 bar 150 C 2205 Duplex NPT 1-1/2" Soda lime 410S13 $299.25 each
35.00 mm 100 bar 150 C 2205 Duplex NPT 2" Soda lime 410S14 $381.23 each
5.00 mm 100 bar 150 C 2205 Duplex NPTF 1/4" Soda lime 413S05 $214.80 each
7.00 mm 100 bar 150 C 2205 Duplex NPTF 3/8" Soda lime 413S06 $231.09 each
11.00 mm 100 bar 150 C 2205 Duplex NPTF 1/2" Soda lime 413S07 $249.15 each
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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.