John Moncrieff: Your Vision for Process Visibility

John Moncrieff Ltd supplies high-quality sight glasses and fittings that deliver clear visibility, rugged reliability, and zero-nonsense performance. From standard viewport hardware to custom-engineered assemblies, we help you monitor, control, and optimise your process—without guesswork.

Why Moncrieff

• Clarity that counts: Optical-grade glass options for fast, unambiguous inspection.
• Engineered to last: Materials and seals designed for pressure, temperature, and chemical exposure.
• Built for your duty: Standard, configurable, or fully bespoke systems—your spec, our execution.
• Quality you can audit: ISO 9001 processes with full material traceability.

Core Product Range

• Inline & spooled sight glasses: Straight-through, rotor, flap, and ball indicators.
• Tank & vessel viewports: Welded, bolted, and flanged styles; circular and rectangular windows.
• Sight flow indicators: Styles P, S, F, T, W, WF, Vista Ball & Spinner variants.
• High-performance windows: Quartz, borosilicate, and toughened soda-lime options.
• Accessories: Guards, shields, illuminators (LED/fluorescent/EEx), gaskets, and engraved scales.

Materials & Ratings

• Bodies: 316/316L stainless, carbon steel, LG2 gunmetal; specialist alloys on request.
• Glasses: Borosilicate, quartz/fused silica, toughened soda-lime; sapphire on request.
• Seals: PTFE, Viton, EPDM, graphite, mica protection where required.
• Pressure/Temperature: Configurations from low-pressure duty up to high-pressure, high-temperature service (product-specific).
• Connections: BSPP/BSPT/NPT, DIN/ANSI flanges, sanitary, and custom patterns.

Applications We Nail

• Chemical & pharmaceutical processing
• Oil & gas, power generation, and steam systems
• Food & beverage, water treatment, and utilities
• Marine & offshore, including flammable and non-flammable services

Compliance & QA

• Standards: PED/CE where applicable; ATEX/EEx options for hazardous areas.
• Inspection: Double QC, dimensional and material certification on request.
• Documentation: CoCs, pressure tests, and packaging to clean-handling protocols.

Bottom line: John Moncrieff delivers sight solutions that look right, install fast, and keep operators informed. No haze. No drama. Just visibility that moves the needle.