Sight Glass Gauges: Reflex, Transparent, Tubular, Bi-Color For China Supplier
Your trusted sourcing partner for sight glass gauges in china—quality instruments at competitive prices.
Are you overwhelmed by too many conflicting quotes?
Are you worried about factory capabilities because tight project deadlines and heavy procurement tasks leave you no time to audit suppliers?
Are you wasting time researching because every factory claims their product is the best, thereby delaying your procurement schedule?
Instrava is here to help you solve your procurement challenges in China.
We serves a global clientele, including EPC contractors, OEM equipment manufacturers, procurement managers, distributors, traders, and engineering consultants. We provide curated product quotations from 3 pre-vetted factories
Standardized Supplier Qualification ProcessEvery manufacturing partner is evaluated through our standardized supplier qualification process before being included in the Instrava sourcing network. The assessment focuses on manufacturing capability, engineering expertise, quality control, delivery reliability, and long-term service support., helping our clients drastically save time on sourcing, screening, and supplier comparison.
Whether you are building new industrial production lines, upgrading and replacing legacy instruments, sourcing for wholesale trade, or requiring custom OEM production, we empower you to secure the most perfectly matched products.
Let’s collaborate for mutual success. With our customer-centric service, Instrava is your trusted procurement partner in China.
A Single Parameter Chart to Master All Sight Glass Gauges
Reflex
Reflex Level Gauge
Reflex Level Gauge is an industrial liquid level measurement device that uses specially designed reflex glass to provide clear level indication. Based on optical reflection principles, the liquid and vapor phases create strong visual contrast for easy reading. It is widely used in boilers, storage tanks, chemical equipment, and high-pressure industrial systems, offering high temperature resistance, pressure durability, and reliable mechanical level monitoring.
| Transparent
Transparent Level Gauge
Transparent Level Gauge is an industrial liquid level indicator featuring a double transparent glass design for direct observation of liquid color, condition, and level changes. It is widely used in chemical, petroleum, power generation, pharmaceutical, and other process industries. The transparent glass structure provides excellent visibility, pressure resistance, and reliable long-term operation for industrial liquid level monitoring applications.
| Tubular
Tubular Glass Gauge
Tubular Glass Level Gauge is a direct reading liquid level measurement instrument designed for industrial tanks and pressure vessels. It uses a transparent glass tube to visually indicate the liquid level inside the equipment. With a durable metal structure and reliable performance, this glass tube level indicator is widely used in boilers, storage tanks, chemical processing equipment, and industrial process control systems.
| Bi-Color
Bi-Color Level Gauge
Bi-Color Level Gauge is a direct reading liquid level indicator that uses red and green color display technology to clearly distinguish liquid and vapor phases. It provides clear and reliable level observation for boilers, pressure vessels, power plants, petrochemical systems, and industrial process applications. The gauge features excellent visibility, stable operation, and customizable designs for various industrial requirements.
When selecting the optimal gauge for your application, keep this simple rule of thumb in mind:
“Transparent for Interfaces, Bi-Color for Steam Boilers, Mica Shields for Corrosive Media.”
Because these gauges operate in critical industrial environments, precision and reliability are paramount. To make an informed purchasing decision, evaluate the following key parameters:
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Process Conditions: Media type, operating temperature, pressure, and fluid corrosiveness
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Mechanical & Connection Specs: Center-to-center distance, mounting orientation, and process connection standards (Flanged / NPT / SW)
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Safety & Protection: Explosion-proof ratings, safety ball check mechanisms, and optional protective enclosures (non-frost extensions, acrylic/mesh guards)
Note: Specifications may vary depending on manufacturer configuration and customization requirements. Please contact us for detailed technical confirmation.
| Product Category | Universal Procurement Parameters (Applicable to All) | Exclusive / Differentiating Parameters | Key Customizable Options | Procurement & Selection Notes |
| Reflex Level Gauge | • Center-to-Center (C-to-C): 300 – 3000 mm • Pressure Rating: Up to PN160 / Class 900 • Operating Temperature: -50°C to +400°C • Process Connection: Flanged (ASME/DIN/JIS), Threaded (NPT/G), Socket Weld (SW) • Wetted Materials: Carbon Steel (A105), SS304, SS316L, Monel, Hastelloy C • Valve Configuration: Isolation valves, vent/drain valves, safety ball check system • Compliance & Certificates: PED 2014/68/EU, ATEX, NACE MR0175, PMI | • Prism Grooves: V-shaped grooved glass structure (single-sided glass) • Visual Contrast: Bright white for gas phase / Dark black for liquid phase | • Center-to-Center distance (precise to ±1mm) • Flange standard & facing (RF/RTJ/FF) • Wetted materials & bolting grade • Drain/vent valve types • Scale plate (SS316 / Aluminum) | Not suitable for liquid-liquid interface measurement or viscous fluids (media clogging the grooves causes refraction failure). |
| Transparent Level Gauge | • Center-to-Center (C-to-C): 300 – 3000 mm • Pressure Rating: Up to PN400 / Class 2500 • Operating Temperature: -196°C to +400°C • Process Connection: Flanged (ASME/DIN/JIS), Threaded (NPT/G), Socket Weld (SW) • Wetted Materials: Carbon Steel (A105), SS304, SS316L, Monel, Hastelloy C • Valve Configuration: Isolation valves, vent/drain valves, safety ball check system • Compliance & Certificates: PED 2014/68/EU, ATEX, NACE MR0175, PMI | • Mica / PTFE Shield: Protects glass from high-temp steam or acidic/alkaline attack • Heating / Cooling Jacket: For insulation or freeze prevention • Non-Frost Extension Block: Acrylic extension for cryogenic service | • Protective Shields (Mica / PCTFE / PTFE) • Heating / Cooling Jackets (Steam/Cooling fluid) • Non-frost extension thickness (75 mm – 250 mm) • Ex-proof illuminator / backlight | Double-sided glass design; costs 30%–50% more than Reflex under high pressure. Preferred choice for oil-water interfaces and corrosive media. |
| Bi-Color High-Pressure Gauge | • Center-to-Center (C-to-C): 300 – 2000 mm • Pressure Rating: Up to 32 MPa+ (Ultra-high pressure) • Operating Temperature: Up to +450°C • Process Connection: High-pressure flanges, Socket Weld / Butt Weld • Wetted Materials: Forged Alloy Steel, SS316L, High-temp Alloy Steels • Valve Configuration: High-pressure needle/chain wheel valves, safety ball check • Compliance & Certificates: ASME Boiler Code, IBR (Indian Boiler Regs), PED | • Backlight Illuminator: Red/Green LED system with optical filters • Trapezoidal Chamber: Refraction design yielding “Red for Steam, Green for Water” • Viewing Angle: Restricted to a 20°–30° visual zone | • Illuminator Voltage (220VAC / 110VAC / 24VDC) • Explosion-proof rating (Ex d IIC T4..T6) • High-temp protective mica shields • Official ASME / IBR certification documents | Specifically designed for high-pressure boiler steam drums. RFQs must verify power supply specs, ex-proof ratings, and boiler certifications. |
| Tubular Glass Gauge | • Center-to-Center (C-to-C): 300 – 2000 mm • Pressure Rating: Low pressure (< 1.0 MPa / Class 150) • Operating Temperature: -20°C to +120°C • Process Connection: 1/2″ – 1″ NPT/G threads, small-size flanges • Wetted Materials: Brass, SS304, SS316 • Valve Configuration: Handwheel isolation valves, simple check valves • Compliance & Certificates: Standard Mill Test Report (MTR), CE | • Borosilicate Glass Tube: Outer diameter 5/8″ (16 mm) or 3/4″ (19 mm) • Protective Guard: Stainless steel mesh cage or acrylic guard tube | • Glass tube outer diameter & wall thickness • Guard mesh material (SS304 / Acrylic) • Quick-drain valve style | Low pressure capacity and fragile. Strictly for atmospheric/low-pressure non-toxic clean liquid tanks. Prohibited in high-pressure or toxic service. |
Carefully Selected Manufacturers, Reliable Industrial Solutions
Instrava is a customer-focused industrial product sourcing partner, helping global buyers identify reliable instruments from China’s manufacturing supply chain.
When customers request a quotation, whether for a single unit or a large-volume project, Instrava focuses on providing suitable product recommendations and competitive solutions based on actual application requirements.
Behind every quotation is a structured manufacturer evaluation process. Instrava carefully selects factories with proven manufacturing experience, typically 10–30 years in their fields, strong engineering capabilities for complex industrial conditions, and the ability to provide customized solutions.
Selected manufacturers have obtained internationally recognized certifications, including CE, UL, ATEX, EAC, IECEx, ABS, and other industry-specific approvals, helping customers reduce supplier selection risks and build more reliable procurement decisions.
Sight Glass Gauges: Unmatched Reliability in Industrial Level Monitoring
As one of the most intuitive and reliable field instruments in industrial automation and process control, Sight Glass Gauges deliver critical, real-time level indication. Their core advantages lie in direct visual observation, inherently safe zero-power operation, and exceptional resistance to high temperatures and extreme pressures.
Engineered with a heavy-duty assembly—including precision gauge bodies, tempered glasses, cover plates, resilient gaskets/cushion pads, high-tensile bolting, safety isolation valves, and vent/drain ports—they are purpose-built for pressure containment, leak prevention, and maximum visibility.
Note:Sealing gaskets and cushion pads are single-use consumables. Never reuse old gaskets during glass replacement to ensure pressure integrity.
| Category | Pressure Range | Applicable Media | Key Advantages |
| Reflex Level Gauge | Medium to High Pressure
(Up to PN160 / Class 900) | Clean liquids, LPG / Liquefied gas | High black-and-white / liquid-gas visual contrast, cost-effective |
| Transparent Level Gauge | High / Ultra-High Pressure
(Up to PN400 / Class 2500) | Colored liquids, liquid-liquid interface measurement, highly corrosive media | Compatible with protective mica shields, supports interface observation and background illumination |
| Bi-Color Gauge Glass | High / Ultra-High Pressure
(Boiler-rated, up to 32 MPa+) | High-pressure steam / Boiler drum water | Distinct red-and-green visual display, highly visible at night and from a distance |
| Tubular Glass Gauge | Low / Atmospheric Pressure
(Typically < 1.0 MPa) | Non-toxic, non-hazardous clean liquids, water, light oils | Highly cost-effective, lightweight structure |
Cross-Industry Applications of Sight Glass Level Gauges
Direct, power-free visual level indication tailored for extreme pressures, corrosive media, cryogenic fuels, and hygienic processes.
Power Generation & High-Pressure Boilers
In thermal power stations, biomass plants, and combined-cycle heat recovery steam generators (HRSG), monitoring high-pressure steam drum levels is critical to prevent catastrophic boiler dry-outs or steam turbine blade erosion.
Bi-Color Sight Glass Gauges
"The side-mounted Bi-Color Gauges with LED backlighting have been performing flawlessly on our storage tanks. The build quality is exceptional, and the vibrant red/green LED contrast makes field inspection fast and safe. Combined with their fast, professional service team, they have proven to be a highly trusted partner for our industrial operations."
— Jürgen Zimmermann, Head of Industrial Purchasing, Munich, Germany
are purpose-built for ultra-high pressure applications (up to 32 MPa and +450°C). Utilizing optical trapezoidal prisms and high-intensity LED backlighting, they produce a sharp, unmistakable “Red for Steam, Green for Water” color transition, enabling operators to read water levels clearly from distance in dark control environments.
Recommended Configuration: Bi-Color Gauges with ASME Section I compliance and protective mica shields.
Oil & Gas Refining and Petrochemicals
Refineries, offshore separators, and distillation units process flammable hydrocarbons requiring explosion-proof and leak-tight visual level monitoring.
Reflex Level Gauges use single-piece grooved prism glasses to create stark black-and-white visual contrast for clean liquids like LPG, gasoline, and naphtha. For oil-water interface separation (such as desalter vessels or condensate tanks), Transparent Level Gauges provide dual-sided glass viewing to let operators monitor fluid separation layers and color boundaries directly.
Recommended Configuration: Reflex Gauges for clean fuels; Transparent Gauges for liquid-liquid interfaces.
Chemical Processing & Acid Production
Aggressive chemicals like sulfuric acid (H₂SO₄), hydrochloric acid (HCl), caustic soda, and corrosive process solvents quickly etch standard gauge glass and degrade metal housings.
Transparent Level Gauges equipped with high-purity Mica Shields or PCTFE/PTFE protective liners prevent chemical attack and glass corrosion under high temperature and pressure. Built with forged 316L Stainless Steel, Monel, or Hastelloy bodies, these gauges deliver long service life without risking catastrophic chemical leaks.
Recommended Configuration: Transparent Gauges with Mica Shields and NACE MR0175 compliant wetted materials.
LPG, LNG & Cryogenic Fuel Storage
Liquefied Petroleum Gas (LPG), Liquefied Natural Gas (LNG), and cryogenic fluids (like liquid nitrogen or ammonia) stored under pressure present severe freezing and condensation challenges.
High-pressure Transparent and Reflex Level Gauges are fitted with customized Acrylic Non-Frost Extension Blocks (ranging from 75mm to 250mm). These extension blocks push ice buildup away from the optical glass, ensuring crystal-clear visual observation even at cryogenic temperatures down to -196°C.
Recommended Configuration: Reflex or Transparent Gauges with Non-Frost Extension Blocks & Ex d Illuminators.
Pharma, Food & Sanitary Utilities
Hygienic processing in biopharmaceuticals, beverage brewing, and dairy plants requires zero liquid dead-legs, easy cleaning, and FDA-compliant materials.
Sanitary-grade Tubular Glass Gauges or low-pressure Transparent Gauges with polished SS316L wetted surfaces, Tri-Clamp process connections, and FDA-certified EPDM/PTFE gaskets ensure strict sanitary compliance while permitting 360° visual inspection of clean CIP fluids and product tanks.
Recommended Configuration: Stainless Steel Sanitary Tubular Gauges with Tri-Clamp connections & FDA gaskets.
Water Treatment & General Utilities
Atmospheric storage tanks, commercial water treatment basins, lube oil reservoirs, and diesel day tanks demand simple, zero-maintenance local level readings without expensive power wiring.
Tubular Glass Gauges offer an economical, lightweight solution for low-pressure (< 1.0 MPa) non-toxic applications. Outfitted with stainless steel protective cages or acrylic shield tubes, they protect the heavy-wall borosilicate glass tube from accidental impact while offering immediate local reading.
Recommended Configuration: Tubular Gauges with Stainless Steel Guard Cage & quick-drain isolation valves.
Sight Glass Level Gauges Ordering Matrix
Interactive configuration matrix for Reflex, Transparent, Tubular, and High-Pressure Bi-Color Glass Level Gauges across Oil & Gas, Power Boilers, Petrochemical, and Hygienic applications.
Prismatic grooved glass (Light/Dark reflection)
Dual flat glass (Corrosive / Interface / Dirty media)
Borosilicate glass tube (Low pressure / Water)
Red/Green optical refraction (High-temp boiler)
Standard thermal shock resistant
High-pressure / High-temp applications
Protection against steam/alkaline erosion
Protection against hydrofluoric acid (HF)
DN15~DN50 / 1/2"~2" (RF, RTJ, Male/Female)
1/2", 3/4", 1" NPT or Socket Weld
Food & Pharma Hygienic Standard
Cryogenic Service
Standard Ambient
Medium Temp
High Temp Steam
Ultra High-Temp Boiler
Auto-close on glass rupture
Allows glass cleaning without removal
Economical isolation valve
Full double isolation valves
Exd IICT6 for night/dark viewing
Prevents ice build-up in sub-zero ops
For heavy viscous or liquid gas media
Request Official B2B Engineering Quotation
Selecting items in the spec matrix above will auto-generate your detailed engineering payload below.
FAQ For Purchasing Sight Glass Gauges
What is the process for purchasing sight glass gauges: reflex, transparent, tubular, bi-color from Instrava supplier？
1. Inquiry (We will respond to your inquiry within 24 hours to confirm specifications and initiate the process.)
2. Quotation (Quotation timelines vary based on the project type and your specific requirements. Standard stock items are quoted within one day, while special orders require three days or a mutually agreed-upon timeframe.)
3. Product Selection (We will present 3–5 product options and pricing for your approval. During this stage, we verify the manufacturer’s production capabilities and relevant national certifications.)
4. Contract, Prepayment, and Production (A 40% prepayment is required to initiate production at a qualified facility. For stock items, we promptly arrange for product testing and packaging.)
5. Interim Payment (Upon successful completion of production and quality inspection, the next 50% of the total amount is due. For stock items, this payment is made after packaging is complete.If the transaction amount does not exceed $50,000, the remaining 60% is paid.)
6. Shipment (You may designate a freight forwarder, or we can arrange shipping for you.)
7. Receipt of Goods (Our Quality Guarantee: When your cumulative order value reaches $50,000, you pay the remaining 10% only after receiving and verifying the product quality. We let our quality do the talking.)
8. After-Sales Service (We actively address and resolve issues through both online and offline channels. We place great importance on after-sales support, as it reflects our responsibility and reputation—the foundation of Instrava’s long-term growth.)
What are the advantages of buying products from Instrava ?
Buying from Instrava gives you the best of both worlds—the direct-from-source pricing of a factory, combined with the professional service, product range, and risk mitigation of an elite sourcing partner. Here is how we deliver value to your business:
Unbiased Market Curation (More Choices & Better Prices): Unlike single factories that only praise their own capacity, or traditional trading companies restricted by personal connection networks, we evaluate the entire Chinese manufacturing landscape. We benchmark and source from multiple verified factories to secure the most competitive pricing and the exact product specifications you need.
100% Transparency (Your “Brain” in China): We never hide behind the veil of being a “fake manufacturer.” We act as your transparent, in-country purchasing department. You always know exactly who is producing your goods, how much they cost, and what the real lead times are.
Uncompromised Quality & Risk Mitigation: Our business is built on long-term partnerships, not one-off high-profit transactions. We perform strict, independent quality control from your perspective before shipment, protecting you from post-purchase defects and communication breakdowns.
Streamlined Communication & Service: No more dealing with slow, production-centric factory service. We provide a single, highly responsive point of contact that manages the entire supply chain—from negotiation and quality checks to shipping logistics—saving you time and reducing headaches.
What types of industrial automation instruments products can you purchase from Instrava?
Level gauge, flowmeter, transmitter, level switch, Gas Alarm Controllers etc.
How to ensure the reliability of the purchased products?
Our customer-centric philosophy prioritizes their procurement needs.
1. Initially confirm the manufacturer based on product pricing and the strength and qualifications of the production factory.
2. Verify the manufacturer’s production environment through video and on-site inspections to check the compliance of the entire product manufacturing process.
3. Ensure post-production product testing and retain data and video evidence from the verification process(testing and verification methods vary depending on the product).
How does Instrava ensure product protection and physical safety during cross-border shipping?
Firstly, we confirm the packaged products with the factory (different products require different packaging and shipping methods. Heavy equipment and bulk shipments are securely secured within sea freight containers using custom-designed engineering steel frames, heavy-duty multi-layer wooden crates, and industrial-grade vacuum rust-proof bags. Precision instruments are protected against impacts and maintained in a stable position; the factory has extensive experience in this area. Custom labels are affixed to the outer packaging).
Secondly, we maintain communication with the freight company to confirm the condition of the goods and advise them to handle the loading and unloading processes with care.
What warranty policies and after-sales technical support does Instrava offer to international customers?
1. Instrava offers a comprehensive 12 to 24-month warranty (specific warranty period depends on the product line), covering all manufacturing and component defects.
2. When online technical support is needed, customers can connect with factory engineers online. Real-time guidance is provided for installation, on-site calibration (for instruments), and commissioning. When on-site engineer support is needed, we will arrange for an engineer to visit the site.
3. In the event of component issues, we will ship replacement parts via international express delivery (DHL/FedEx) to minimize your project downtime.
4. Whether a product requires replacement or repair will be clearly stated in the purchase contract.
Why Trust Instrava?
We select manufacturers from a neutral, impartial standpoint, always with your best interests in mind.
Our very existence depends on helping you source the products that are the perfect fit for your needs.
Based in China, we are able to conduct on-site inspections of production environments and product quality firsthand.
We help you avoid intermediaries posing as factories.
We facilitate smoother after-sales support, eliminating time zone issues and the delays often associated with dealing directly with factories.
Our multilingual team ensures effective communication.
For a trading startup, every interaction with a client is a precious opportunity—a sign that you are willing to place your trust in us and give us the chance to prove ourselves.
In the digital age, while information is easily accessible, misconceptions often cloud the trust between people.
Instrava relies entirely on trust; it is our core philosophy and the foundation of our existence in society. It is the fundamental basis for our long-term growth and our commitment to serving the community.
Please place your trust in us.
