NPT 1-1/2″ Hastelloy C-22 Threaded Fused Sight Glass Borosilicate Window for Hydraulic Oils Compressed Air

  • Fused Glass-to-Metal Hermetic Seal: Zero leak paths, zero maintenance — the glass is permanently fused into the housing, eliminating O-ring degradation and ensuring reliable containment under thermal cycling.
  • Hastelloy C-22 Corrosion Resistance: Withstands pitting, crevice corrosion, and stress cracking in aggressive chemical, marine, and high-temperature environments where 316 stainless steel falls short.
  • Extreme Pressure & Temperature Rating: Borosilicate window handles up to 100 bar and -58°C to 300°C, delivering optical clarity and thermal shock resistance for demanding hydraulic and process applications.
  • OEM-Ready Customization: Beyond NPT, Fanovo offers tailored thread types (BSP/G), materials, coatings, and dimensions — with in-house prototyping and manufacturing to match your exact equipment specs.
  • Certified Quality & Full Support: ISO 9001-certified, NSF/ANSI 61 and CE compliant, backed by a two-year warranty, full traceability, and responsive engineering support.
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The NPT 1-1/2″ Hastelloy C-22 Threaded Fused Sight Glass is a premium visual monitoring solution engineered for demanding industrial applications. Designed for use with hydraulic oils, compressed air systems, refrigerants, and water heaters, this sight glass combines the exceptional corrosion resistance of Hastelloy C-22 with the thermal stability of a borosilicate window.

Engineered for safety and longevity, the glass-to-metal fusion process creates a hermetically sealed one-piece construction with the glass under permanent compression. This pre-stressed design delivers outstanding mechanical strength that prevents glass separation — even under severe temperature cycling and pressure fluctuations — making this high pressure sight glass a reliable choice for critical process monitoring. The NPT threaded connection conforms to ASME B1.20.1 for secure, leak-proof installation with zero maintenance requirements over its long service life.

SpecificationDetail
Product TypeThreaded Fused Sight Glass / High Pressure Sight Glass
Thread StandardNPT 1-1/2″ (ASME B1.20.1)
Housing MaterialHastelloy C-22 — superior corrosion and oxidation resistance
Window MaterialBorosilicate — excellent thermal shock and chemical resistance
Max Operating Temperature300°C
Min Operating Temperature-58°C
Max Operating Pressure100 bar / 1450 PSIG
Aperture Diameter30 mm
Hex Size55 mm
Applicable MediaHydraulic oils, compressed air, refrigerants, water heaters
CertificationsNSF/ANSI 61, UPC/CE, ISO 9001, Lead Free Compliant

Applications

Built for demanding environments, this hydraulic sight glass and compressor sight glass is ideal for use in:

  • Hydraulic power units and oil reservoirs — real-time oil level sight glass monitoring for fluid condition and level verification

  • Compressed air systems and air dryers — visual inspection of condensate and oil carryover

  • Lubrication systems for gearboxes, pumps, and compressors

  • Industrial pipelines and process vessels — as an inline sight glass or pipeline sight glass for flow observation

  • High-temperature and high-pressure fluid systems

Why Choose This Fused Sight Glass

Unlike conventional sight glasses with O-rings or gaskets that degrade over time, the fused glass-to-metal design eliminates potential leak paths. The borosilicate window provides exceptional optical clarity and withstands thermal shock, while the Hastelloy C-22 body offers unmatched resistance to pitting, stress corrosion cracking, and oxidation — making it the ideal choice for harsh chemical and high-temperature services.

Aperture Diameter30 mm
Thread StandardNPT 1-1/2 (complies with ASME B1.20.1)
Housing MaterialHastelloy C-22
Window MaterialBorosilicate
Maximum Operating Temperature300 °C
Minimum Operating Temperature-58 °C
Maximum Operating Pressure100 bar
Hex Size55 mm
Nominal Diameter1.90 inch
Threads Per InchThreads Per Inch
Thread Count8±1/4
Applicable MediaHydraulic oils, refrigerants, water heaters, compressed air

Complies with Lead Free Plumbing Laws, NSF/ ANSI 61, UPC/ CE, ISO 9001

For approval information, please refer to the products specification sheet. For any other information on product certification and documentation information, please contact Fanovo.

FANOVO STATEMENT OF WARRANTY & LIMITATION OF WARRANTY

Fanovo warrants, to our all purchasers, that its products which are delivered to its purchasers will be the kind described in the order or price list and will be free of defects in workmanship or material for a period of two year from the date of shipping to you, our purchaser.

Should any failure to conform to this warranty appear within two year after the date of the initial delivery to our purchaser, Fanovo will, upon written notification thereof and substantiation that the goods have been stored, installed, maintained and operated in accordance with Fanovo’s recommendation and standard industry practice, correct such defects by suitable repair or replacement at Fanovo’s own expense. If any valve alleged to be defective, is reported to Fanovo headquarter in China, it will be examined and, if found to be defective under the warranty, it will be replaced at no charge in future order.

THIS WARRANTY IS EXCLUSIVE AND IS IN LIEU OF ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR OTHER WARRANTY OF QUALITY, WHETHER EXPRESS OR IMPLIED, EXCEPT THE WARRANTY OF TITLE AND AGAINST PATENT INFRINGEMENT Correction of non-conformities, in the manner and for the period of time provided above, shall constitute fulfillment of all liabilities of Fanovo to our purchaser, with respect to the goods, whether based on contract, negligence, strict tort or otherwise, it is the intention of Fanovo that no warranty of any kind, whether express or implied, shall pass through our purchaser to any other person or corporation.

LIMITATION OF LIABILITY: FANOVO SHALL NOT UNDER ANY CIRCUMSTANCES BE LIABLE FOR SPECIAL OR CONSEQUENTIAL DAMAGES SUCH AS, BUT NOT LIMITED TO, DAMAGES OR LOSS OF OTHER PROPERTY OR EQUIPMENT, LOSS OF PROFITS, OR REVENUE, COST OF CAPITAL, COST OF PURCHASED OR REPLACEMENT GOODS, OR CLAIMS OF CUSTOMERS OF OUR INITIAL PURCHASER. THE REMEDIES OF OUR INITIAL PURCHASER, AND ALL OTHERS, SET FORTH HEREIN ARE EXCLUSIVE, AND THE LIABILITY OF FANOVO WITH RESPECT TO SAME SHALL NOT, EXCEPT AS EXPRESSLY PROVIDED HEREIN, EXCEED THE PRICE OF GOODS UPON WHICH SUCH LIABILITY IS BASED.

Fanovo is not just innovative products—we also provide wide-ranging capabilities, including design, manufacturing, and distribution. Each of these capabilities, as well as others, can be scaled to your needs – you can use as much or as little as makes sense for your product development.

Our Strengths

  • Design/Prototyping
  • Manufacturing & Assembly
  • Custom Labeling & Packaging
  • Inventory Management
  • Continuous Improvement & Refinement

If you’re looking for an established, financially secure partner who offers robust quality systems, validated processes, continuous improvement strategies, and a proven track record, you’ve come to the right place. Contact us and we will show you the major breakthroughs OEMs have experienced with us

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