Reset All
NPT Sight Glasses
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 LLC
NPT-Threaded High Pressure Sight Glasses with Quartz Windows, 17-4PH Steel Housing

Sight windows 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. This sight glass is an 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.
Aperture Dia. | Thread | Max Operating Temp. | Housing Material | Max Operating Pressure | Window Material | Mfg P/N | Encole P/N | Price | |
---|---|---|---|---|---|---|---|---|---|
0.35 inch | NPT 3/8 | 65 C | 17-4PH | 6170 psi | Quartz | 100765 | 769E701 | $ 408.00 each | |
0.40 inch | NPT 1/2 | 60 C | 17-4PH | 6170 psi | Quartz | 100766 | 769E702 | $ 426.04 each | |
0.55 inch | NPT 3/4 | 55 C | 17-4PH | 6170 psi | Quartz | 100767 | 769E703 | RFQ | |
0.75 inch | NPT 1 | 45 C | 17-4PH | 6170 psi | Quartz | 100768 | 769E704 | $ 435.90 each | |
1.01 inch | NPT 1-1/4 | 40 C | 17-4PH | 6170 psi | Quartz | 100769 | 769E705 | RFQ | |
1.22 inch | NPT 1-1/2 | 40 C | 17-4PH | 6170 psi | Quartz | 100770 | 769E706 | $ 697.58 each | |
1.61 inch | NPT 2 | 35 C | 17-4PH | 6170 psi | Quartz | 100771 | 769E707 | RFQ |
Metaglas, Herberts Industrieglas GmbH & Co. KG
Fused NPT Sight Glasses, Duplex Steel 2205, Sodalime, Full Glass Height

Glass is flush with both ends of the housing. Sides of the glass are flat and polished to approximately S-D: 80-40, which is an optical finish of a typical room window. This optical clarity is suitable for undistorted viewing through 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. | Thread | Max Operating Temp. | Max Operating Pressure | Housing Material | Window Material | Mfg P/N | Encole P/N | Price | |
---|---|---|---|---|---|---|---|---|---|
5 mm | NPT 1/4 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62-025S | 774E1601 | $ 214.08 each | |
5 mm | NPTF 1/4 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62F-025S | 774E1602 | $ 219.80 each | |
7 mm | NPT 3/8 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62-038S | 774E1603 | $ 231.05 each | |
7 mm | NPTF 3/8 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62F-038S | 774E1604 | $ 254.60 each | |
11 mm | NPT 1/2 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62-050S | 774E1605 | $ 248.12 each | |
11 mm | NPTF 1/2 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62F-050S | 774E1606 | $ 268.90 each | |
19 mm | NPT 3/4 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62-075S | 774E1607 | $ 262.12 each | |
19 mm | NPTF 3/4 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62F-075S | 774E1608 | $ 290.52 each | |
17 mm | NPT 1 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62-100S | 774E1609 | $ 283.15 each | |
17 mm | NPTF 1 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62F-100S | 774E16010 | $ 302.90 each | |
22 mm | NPT 1-1/4 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62-125S | 774E16011 | $ 288.05 each | |
22 mm | NPTF 1-1/4 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62F-125S | 774E16012 | $ 315.64 each | |
25 mm | NPT 1-1/2 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62-150S | 774E16013 | $ 299.25 each | |
25 mm | NPTF 1-1/2 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62F-150S | 774E16014 | $ 342.50 each | |
35 mm | NPT 2 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62-200S | 774E16015 | $ 381.23 each | |
35 mm | NPTF 2 | 150 C | 100 bar | Duplex 2205 | Soda lime | Met-62F-200S | 774E16016 | $ 429.80 each |
Oil-Rite Corporation
Stainless Steel Gasketed Glass Sights with NPT Threads

303 Stainless Steel Gasketed Glass Sight for visual observation of liquid levels and condition. This sight glass is typically used in any application where oil or fluid inspection is essential. The housing is a 303 Stainless Steel fitting with U.S. standard NPT threads conforming to ASME B1.20.1.
Aperture Dia. | Thread | Max Operating Pressure | Max Operating Temp. | Housing Material | Window Material | Mfg P/N | Encole P/N | Price | |
---|---|---|---|---|---|---|---|---|---|
0.312 inch | NPT 1/4 | 125 psi | 225 F | AISI 303 | Soda lime | B4763-01B | 776E801 | $ 59.26 per package of 2 | |
0.470 inch | NPT 3/8 | 125 psi | 225 F | AISI 303 | Soda lime | B4763-02B | 776E802 | $ 65.32 per package of 2 | |
0.594 inch | NPT 1/2 | 125 psi | 225 F | AISI 303 | Soda lime | B4763-03B | 776E803 | $ 77.32 per package of 2 | |
0.781 inch | NPT 3/4 | 125 psi | 225 F | AISI 303 | Soda lime | B4763-04B | 776E804 | $ 85.32 per package of 2 | |
1.000 inch | NPT 1 | 100 psi | 225 F | AISI 303 | Soda lime | B4763-05B | 776E805 | $ 93.78 each | |
1.531 inch | NPT 1-1/4 | 75 psi | 225 F | AISI 303 | Soda lime | B4763-06B | 776E806 | $ 61.90 each | |
1.593 inch | NPT 1-1/2 | 50 psi | 225 F | AISI 303 | Soda lime | B4763-07B | 776E807 | $ 72.67 each | |
1.970 inch | NPT 2 | 50 psi | 225 F | AISI 303 | Soda lime | B4763-08B | 776E808 | $ 86.75 each |
Metaglas, Herberts Industrieglas GmbH & Co. KG
NPT-Threaded Fused Sight Glasses, Borosilicate Windows

Metaglas fused sight glasses for use with all common hydraulic oils, refrigeration, water heaters, and compressed air applications. Fusing glass to metal creates a strong, hermetically sealed single-piece part. These sight windows have NPT threads conforming to ASME B1.20.1.
Aperture Dia. | Thread | Housing Material | Max Operating Temp. | Max Operating Pressure | Window Material | Mfg P/N | Encole P/N | Price | |
---|---|---|---|---|---|---|---|---|---|
9 mm | NPT 1/4 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-025H | 770E3601 | $ 287.54 each | |
9 mm | NPTF 1/4 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-F-025H | 770E3602 | $ 352.60 each | |
10 mm | NPT 3/8 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-038H | 770E3603 | $ 333.95 each | |
10 mm | NPTF 3/8 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-F-038H | 770E3604 | $ 375.60 each | |
14 mm | NPT 1/2 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-050H | 770E3605 | $ 378.50 each | |
14 mm | NPTF 1/2 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-F-050H | 770E3606 | $ 415.25 each | |
18 mm | NPT 3/4 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-075H | 770E3607 | $ 435.90 each | |
18 mm | NPTF 3/4 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-F-075H | 770E3608 | $ 465.30 each | |
22 mm | NPT 1 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-100H | 770E3609 | $ 540.00 each | |
22 mm | NPTF 1 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-F-100H | 770E36010 | $ 587.20 each | |
25 mm | NPT 1-1/4 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-125H | 770E36011 | $ 622.00 each | |
25 mm | NPTF 1-1/4 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-F-125H | 770E36012 | $ 675.20 each | |
30 mm | NPT 1-1/2 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-150H | 770E36013 | $ 712.00 each | |
30 mm | NPTF 1-1/2 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-F-150H | 770E36014 | $ 768.90 each | |
37 mm | NPT 2 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-200H | 770E36015 | $ 1370.00 each | |
37 mm | NPTF 2 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-F-200H | 770E36016 | $ 1410.80 each | |
55 mm | NPT 3 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-300H | 770E36017 | $ 2321.00 each | |
55 mm | NPTF 3 | Hastelloy C-22 | 300 C | 100 bar | Borosilicate | Met-61-F-300H | 770E36018 | $ 2482.50 each | |
9 mm | NPT 1/4 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-025S | 770E36019 | $ 181.27 each | |
9 mm | NPTF 1/4 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-F-025S | 770E36020 | $ 187.90 each | |
10 mm | NPT 3/8 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-038S | 770E36021 | $ 189.55 each | |
10 mm | NPTF 3/8 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-F-038S | 770E36022 | $ 195.60 each | |
14 mm | NPT 1/2 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-050S | 770E36023 | $ 198.32 each | |
14 mm | NPTF 1/2 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-F-050S | 770E36024 | $ 216.27 each | |
18 mm | NPT 3/4 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-075S | 770E36025 | $ 209.24 each | |
18 mm | NPTF 3/4 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-F-075S | 770E36026 | $ 231.50 each | |
22 mm | NPT 1 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-100S | 770E36027 | $ 218.53 each | |
22 mm | NPTF 1 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-F-100S | 770E36028 | $ 242.80 each | |
25 mm | NPT 1-1/4 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-125S | 770E36029 | $ 288.89 each | |
25 mm | NPTF 1-1/4 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-F-125S | 770E36030 | $ 297.60 each | |
30 mm | NPT 1-1/2 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-150S | 770E36031 | $ 291.08 each | |
30 mm | NPTF 1-1/2 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-F-150S | 770E36032 | $ 309.70 each | |
37 mm | NPT 2 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-200S | 770E36033 | $ 386.59 each | |
37 mm | NPTF 2 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-F-200S | 770E36034 | $ 398.65 each | |
55 mm | NPT 3 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-300S | 770E36035 | $ 496.94 each | |
55 mm | NPTF 3 | Duplex 2205 | 280 C | 100 bar | Borosilicate | Met-61-F-300S | 770E36036 | $ 532.80 each |
Oil-Rite Corporation
Low Cost Fused NPT-Threaded Sight Glasses, Zinc-Plated Carbon Steel

Sodalime glass is fused to a plain carbon steel body which is Zinc-plated for added corrosion resistance. These sight glasses are an ideal budget choice for visual observation of liquid levels and their colors, present or absence of refrigerant, oil levels in a compressor. Applications include hydraulic systems with mineral oils, diesel, and other common liquids where low cost is required. Not suitable for cycling high temperature, high pressure or aggressively corrosive applications.
Aperture Dia. | Thread | Max Operating Temp. | Max Operating Pressure | Housing Material | Window Material | Mfg P/N | Encole P/N | Price | |
---|---|---|---|---|---|---|---|---|---|
0.340 inch | NPT 1/4 | 130 F | 125 psi | Carbon Steel Zinc-Plated | Soda lime | A2890-1 | 775E801 | $ 53.25 per package of 3 | |
0.560 inch | NPT 1/2 | 130 F | 125 psi | Carbon Steel Zinc-Plated | Soda lime | A2890-3 | 775E802 | $ 68.90 per package of 3 | |
0.940 inch | NPT 1 | 130 F | 125 psi | Carbon Steel Zinc-Plated | Soda lime | A2890-5 | 775E803 | $ 58.79 per package of 2 | |
1.190 inch | NPT 1-1/4 | 130 F | 125 psi | Carbon Steel Zinc-Plated | Soda lime | A2890-6 | 775E804 | $ 75.45 per package of 2 | |
1.440 inch | NPT 1-1/2 | 130 F | 125 psi | Carbon Steel Zinc-Plated | Soda lime | A2890-7 | 775E805 | $ 31.90 each | |
1.880 inch | NPT 2 | 130 F | 125 psi | Carbon Steel Zinc-Plated | Soda lime | A2890-8 | 775E806 | $ 38.75 each | |
0.440 inch | NPTF 3/8 | 130 F | 125 psi | Carbon Steel Zinc-Plated | Soda lime | A2890-2 | 775E807 | $ 68.80 per package of 2 | |
0.750 inch | NPTF 3/4 | 130 F | 125 psi | Carbon Steel Zinc-Plated | Soda lime | A2890-4 | 775E808 | $ 74.24 per package of 2 |
Oil-Rite Corporation
Reflector Sight Glass in Stainless Steel, Gasketed, NPT Threads

Reflector behind the glass helps see oil levels, presence of liquids, color, quality of a fluid. 303 Stainless Steel Gasketed Glass Sight for visual observation of liquid levels and their condition. These sight glasses are typically used in any application where oil or fluid inspection is essential. The housing is a 303 Stainless Steel fitting with U.S. standard NPT threads conforming to ASME B1.20.1. Use traditional installation tools and Teflon tape or pipe sealant. These sight glasses have a Buna-N internal seal for good chemical compatibility with Petroleum oils and fluids; Cold Water; Silicone greases and oils; Dibasic Acid Ester (Diester) based lubricants (MIL-L-7808); Ethylene glycol base fluids (Hydrolubes). Not Recommended for: Halogenated hydrocarbons (carbon tetrachloride, trichloroethylene); Nitro hydrocarbons (nitrobenzene, aniline); Phosphate ester hydraulic fluids (Skydrol, Fyrquel, Pydraul); Ketones (MEK, acetone); Strong Acids Ozone; Automotive brake fluid.
Aperture Dia. | Thread | Max Operating Pressure | Max Operating Temp. | Housing Material | Window Material | Mfg P/N | Encole P/N | Price | |
---|---|---|---|---|---|---|---|---|---|
0.470 inch | NPT 3/8 | 125 psi | 225 F | AISI 303 | Soda lime | B4763-12B | 777E701 | $ 71.32 per package of 2 | |
0.594 inch | NPT 1/2 | 125 psi | 225 F | AISI 303 | Soda lime | B4763-13B | 777E702 | $ 81.32 per package of 2 | |
0.781 inch | NPT 3/4 | 125 psi | 225 F | AISI 303 | Soda lime | B4763-14B | 777E703 | $ 93.32 per package of 2 | |
1.000 inch | NPT 1 | 100 psi | 225 F | AISI 303 | Soda lime | B4763-15B | 777E704 | $ 95.32 per package of 2 | |
1.531 inch | NPT 1-1/4 | 75 psi | 225 F | AISI 303 | Soda lime | B4763-16B | 777E705 | $ 64.67 each | |
1.593 inch | NPT 1-1/2 | 50 psi | 225 F | AISI 303 | Soda lime | B4763-17B | 777E706 | $ 74.85 each | |
1.970 inch | NPT 2 | 50 psi | 225 F | AISI 303 | Soda lime | B4763-18B | 777E707 | $ 89.65 each |