Lined Sight Flow Indicators
Lined Sight Flow Indicators
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Full technical data and dimensions
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PTFE Lined Double Window Sight Flow Indicator
Lined double window sight glass, NB 1/2" to 16"
Lined sight flow indicator with two opposed windows — look straight through the line against the light. NB 1/2" to 16", lined in PFA or FEP.
| Product type | Lined double window sight flow indicator |
|---|---|
| Body / steel grade | ASTM A 216 Gr. WCB |
| Lining material | PTFE / PFA / FEP |
| Liner standard | ASTM D 3307 (PFA), ASTM D 4894-19 |
| Lining options | Virgin or anti-static (conductive black) PTFE to ASTM D 4894 & D 4895, PFA to ASTM D 3307, FEP to ASTM D 2116 |
| Flange standard | ASME/ANSI B16.5 |
| Flange class | Class 150 standard; Class 300 on request |
| Size range | NB 1/2" to NB 16" |
Product overview
What it does, and where it fits.
Two windows set opposite each other let an operator look straight through the flow with a light behind it. That reads far better than a single window for judging colour, clarity, phase separation and entrained gas, because the light passes through the fluid rather than reflecting off it.
The lined version keeps the body, and everything the fluid touches apart from the glass, in fluoropolymer — so a sight glass can be put into an aggressive line without becoming its weak point. Body is a casting to ASTM A 216 Gr. WCB, flanged to ASME/ANSI B16.5 Class 150.
Face-to-face steps up sharply from NB 8": 274 mm at NB 6" against 610 mm at NB 8", reaching 1114 mm at NB 16". Allow for that when setting out larger lines.
Features
Built into every unit.
- Two opposed windows for through-illumination viewing
- NB 1/2" to 16", face to face 131 mm to 1114 mm
- Cast body to ASTM A 216 Gr. WCB, lined and flanged to B16.5 Class 150
- Special face-to-face lengths on request
- Stainless steel body on request
Benefits
Why it earns its place in the line.
- Through-illumination reads colour, clarity and phase separation far better than a single window
- Fluoropolymer lined body — the sight glass is not the corrosion point of the line
- Outstanding corrosion resistance to aggressive organic and inorganic chemicals across a wide temperature range
- Non-stick, non-wetting bore — low surface energy keeps product moving and simplifies cleaning
- Chemically inert and pure; no additives, plasticisers, stabilisers or lubricants to contaminate the process fluid
- The lowest coefficient of friction of any solid, reducing pressure drop and deposit build-up
Applications & industries
Where it is specified.
Typical applications
- Visual confirmation of flow on corrosive lines
- Watching for phase separation, colour change or entrained gas
- Reactor discharge and transfer line monitoring
- Confirming a line has drained before maintenance
Industries served
- Chemical processing
- Pharmaceutical
- Petrochemical
- Oil & gas
- Power generation
- Pulp & paper
- Mining & metallurgy
- Agrochemicals & dyes
Technical data
Specification for PTFE Lined Double Window Sight Flow Indicator.
Figures below are for this product only — every item in the range carries its own dimension table.
| Product type | Lined double window sight flow indicator |
|---|---|
| Body / steel grade | ASTM A 216 Gr. WCB |
| Lining material | PTFE / PFA / FEP |
| Liner standard | ASTM D 3307 (PFA), ASTM D 4894-19 |
| Lining options | Virgin or anti-static (conductive black) PTFE to ASTM D 4894 & D 4895, PFA to ASTM D 3307, FEP to ASTM D 2116 |
| Flange standard | ASME/ANSI B16.5 |
| Flange class | Class 150 standard; Class 300 on request |
| Size range | NB 1/2" to NB 16" |
| Temperature range | Continuous service to 260 °C (PTFE melting point 327 °C, PFA 306 °C, FEP 260 °C) |
| Pressure rating | ASME/ANSI B16.5 Class 150 flanges as standard; Class 300 available on request |
| Manufacturing standard | ASTM F 1545 |
| Spark testing | Every lined component spark tested at 5000 × E volts (E = liner thickness in mm), to a maximum of 15 000 V |
| Hydro testing | Hydrostatic or pneumatic test according to the lining technique; hydrostatic test on components with vent holes |
| Inspection | Dimensional and visual examination of liner and steel parts — weld aspect, overall dimensions, collar size, liner thickness, surface flaws and paint thickness |
| External protection | Zinc epoxy primer, minimum 60 μm dry film, over steel sand-blasted to SA 2.5 |
| Certification | EN 10204 3.1 mill certificates and FDA certification for the fluoropolymer available on request |
| Face to face | 131 mm to 1114 mm, tolerance ±2 mm |
| Size | Face to face L (±2) | PTFE | PFA | FEP |
|---|---|---|---|---|
| 1" | 131 | — | ✓ | ✓ |
| 1.5" | 169 | — | ✓ | ✓ |
| 2" | 182 | — | ✓ | ✓ |
| 3" | 207 | — | ✓ | ✓ |
| 4" | 233 | — | ✓ | ✓ |
| 6" | 274 | — | ✓ | ✓ |
| 8" | 610 | — | ✓ | ✓ |
| 10" | 742 | — | ✓ | ✓ |
| 12" | 862 | — | ✓ | ✓ |
| 14" | 994 | — | ✓ | ✓ |
| 16" | 1114 | — | ✓ | ✓ |
All dimensions in mm. Face-to-face steps up sharply from NB 8" — allow for it when setting out larger lines.
Available on request
- Special length (face to face)
- Stainless steel body
FAQ
Questions we are asked about this item.
The catalogue lists 274 mm at NB 6" and 610 mm at NB 8", reflecting a change in body construction at that size. Take the figure from the table rather than interpolating.
Yes — special length (face to face) is listed as available on request.
Related products
Commonly specified alongside PTFE Lined Double Window Sight Flow Indicator.
Double Window Sight Flow Indicators
Lined Pipes & Spools
Spacers, Bellows, Strainers & Accessories
Enquiry
Tell us your line size — we'll confirm the spec.
Send the bore, the media, the temperature and pressure, and the flange standard you work to. Drawings and custom sizes welcome.
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