FSG003 3/8″ 1/2″ 3/4″ 1″ NPT Thread Hexagon Brass Coolant Sight Plug Air Compressor Sight Gauge Oil Level Sight Glass In Reservoirs And Radiators

Why This Sight Gauge Stands Out:

  • Hexagon body design – Easy wrench-tightening, secure fit every time

  • Solid brass construction – Built for industrial durability, resists corrosion

  • Multiple glass options – Choose natural, tempered, or borosilicate glass for your temperature needs (up to 120°C)

  • Wide thread compatibility – Available in NPT, NPTF, UNC, UNF, Metric, and BSP (G thread)

  • Versatile seal choices – Viton, FKM, NBR, Aramid gasket, or copper seal

Custom Options:

  • Sizes: 3/8″ to 2″ full range

  • Threads: NPT, BSP, Metric, UNC, UNF

  • Glass thickness: 2mm – 5mm

  • OEM: Custom labeling, packaging, design

Perfect for: Air Compressors │ Gearboxes │ Pumps │ Oil Receivers │ Speed Reducers │ Power Transmission Systems

Certified Quality: NSF/ANSI 61 │ CE │ ISO 9001 │ Lead-Free Compliant

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( FSG003 ) is your definitive solution for reliable, direct fluid level and flow observation in industrial equipment. Engineered as a robust brass oil level sight glass, its one-piece hexagonal design ensures superior durability and leak-proof performance, making it an essential component for any air compressor, gearbox, or hydraulic system.

Built for Industrial Reliability
Unlike multi-part “sandwiched” glass designs, our sight plug features a solid brass body fused directly to a high-strength glass window (Tempered or Borosilicate options available). This robust construction eliminates common failure points, provides excellent resistance to corrosion, and withstands pressures up to 1MPa (145 psi). It is the ideal upgrade for ensuring operational integrity in demanding environments like reservoirs and radiators.

Simplified Installation & Maintenance (OEM & MRO)
The standard hexagon head is a key feature for efficiency. It allows for fast, secure installation using a common wrench, drastically reducing assembly time for OEM manufacturers and simplifying field replacement for maintenance (MRO) professionals. No special tools are required. This straightforward design makes it a top choice as a coolant sight plug or general-purpose fluid viewer.

Full Specification & Customization
We provide a comprehensive range of options to meet your exact engineering needs.

Model: FSG003
Body Material: Solid Brass
Thread Types: NPT, NPTF, BSP (G), UNC, UNF, and Metric
Available Sizes: 3/8″, 1/2″, 3/4″ up to 2″
Pressure Rating: Max 1MPa (145 psi)
Temperature Range: -30°C to 120°C
Primary Applications: Air Compressors, Gearboxes, Hydraulic Tanks, Pumps, Oil Receivers, Speed Reducers.
Glass Options: Natural, Tempered, Borosilicate Glass

Contact us for OEM quotes, specific size configurations, or to discuss your application requirements.

ParameterSpecification
Thread Size3/4″ NPT (Male)
Body MaterialSolid Brass (Corrosion-Resistant)
Window MaterialTempered Glass (High-Strength)
Sealing MaterialFKM (Viton®) / HNBR / Copper Ring
Max. Pressure116 PSI (Standard) – Up to 1500 PSI available
Max. Temperature120°C / 248°F (Standard) – Up to 350°C / 662°F available
Media CompatibilityOil, Water, Air, Light Oil
Custom ItemAvailable Options
Thread TypesNPT, BSP, Metric (M)
Size Range1/4″ – 2″
Seal OptionsFKM (Viton®) for high-temp, HNBR, Copper, Viton O ring
Body MaterialsBrass, Bronze, 316 Stainless Steel, Aluminum
OEM ServicesCustom labeling, packaging, design, prototyping
Wall Thickness1mm to 1.5mm with holes
Special DesignCustomized structure and size per requirements
ItemDetails
Manufacturing CapabilityFanovo Industries manufactures multiple styles of sight glass plugs
Size CustomizationStandard and custom sizes available per client needs
Material CustomizationMultiple housing and sealing material options
Performance CustomizationCustom pressure and temperature ratings
OEM SupportFull custom labeling, packaging, design and prototyping
Technical SupportProfessional technical consultation for special demands
Application AdaptabilitySuitable for oil, water, air and light oil media

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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