Flowserve PFA Sight Glass | For Aggressive Media

Industrial sight glass, PTFE-lined, flanged, DN80 PN16

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PFA Plug Valves

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PFA Check Valves

PFA Ball Valves

PFA Strainers

PRODUCT CONFIGURATOR

The Flowserve PFA Sight Glass Program

As an authorized partner, we offer a comprehensive range of PFA sight glasses from the renowned Atomac brand by Flowserve. The ASG and ARV/SG series stand for the highest quality in chemical plant engineering.

Series & Type	Nominal Sizes & Connection	Technical Specifications	Special Features & Advantages
ASG Standard Sight Glass	Nominal sizes: DN40 - DN200 Connection: DIN EN 1092-2 PN16	Body: Ductile iron GGG40.3 Lining: Full PFA lining Glass: Borosilicate glass according to DIN 7080	Classic flow sight glass for visual monitoring Solid body with full PFA lining Highest chemical resistance for aggressive media
ARV/SG Combination Check Valve/Sight Glass	Nominal sizes: DN25 - DN100 Connection: DIN EN 1092-2 PN16	Function: Ball check valve with sight glass Ball: Solid PTFE ball Body: PFA-lined	Combines visual flow monitoring with backflow prevention Compact valve for horizontal and vertical piping systems Solid PTFE ball for reliable tightness

Series & Type

Nominal Sizes & Connection

Technical Specifications

Special Features & Advantages

ASG

Standard Sight Glass

Nominal sizes: DN40 - DN200
Connection: DIN EN 1092-2 PN16

Body: Ductile iron GGG40.3
Lining: Full PFA lining
Glass: Borosilicate glass according to DIN 7080

Classic flow sight glass for visual monitoring
Solid body with full PFA lining
Highest chemical resistance for aggressive media

ARV/SG

Combination Check Valve/Sight Glass

Nominal sizes: DN25 - DN100
Connection: DIN EN 1092-2 PN16

Function: Ball check valve with sight glass
Ball: Solid PTFE ball
Body: PFA-lined

Combines visual flow monitoring with backflow prevention
Compact valve for horizontal and vertical piping systems
Solid PTFE ball for reliable tightness

The ASG sight glasses are classic flow sight glasses with a solid body made of ductile iron GGG40.3 and full PFA lining. The ARV/SG series combines visual flow monitoring with reliable backflow prevention in a compact valve – ideal for horizontal and vertical piping systems.

Technical Features and Applications

All models come standard with flange connections according to DIN EN 1092-2 (PN16), housing length according to EN 558 series 1, and are suitable for operating pressures up to 16 bar. The viewing windows are made of borosilicate glass according to DIN 7080 – transparent and resistant to high temperatures. On request, versions with ASME B16.5 Class 150 flanges are also available.

Typical applications for PFA sight glasses include:

Chemical production (acids, bases, solvents)
Pharmaceutical industry (high-purity substances)
Semiconductor manufacturing (ultra-pure chemicals)
Surface treatment and food industry (e.g., CIP processes)

Availability and Quality at FERGO

All Flowserve PFA sight glasses are manufactured to high-quality standards. FERGO keeps various types in stock – both DIN and ANSI versions in the most requested nominal sizes. Our technical team is happy to assist in selecting the right sight glass for your specific application.

Frequently Asked Questions – PFA Valves

A PFA-lined valve combines the mechanical strength of a ductile iron (GGG40.3) outer body with a seamless inner lining of PFA (Perfluoroalkoxy) – a fully fluorinated thermoplastic from the PTFE family with near-universal chemical resistance. The construction principle:

Outer body: Ductile cast iron EN-GJS-400-15 (GGG40.3) provides the pressure-bearing shell, flange geometry, and mechanical robustness. The iron never contacts the process medium.
PFA lining: All wetted surfaces – body bore, flanges, closure element (ball, disc, plug), stem seal area, and internals – are completely encapsulated in a thick, monolithic PFA liner. The liner is bonded or compression-fitted to the iron body to form a single leak-free unit.
No metallic contact with medium: Because the PFA liner fully isolates all iron and steel components from the process fluid, PFA valves can handle virtually any chemical that would corrode or contaminate stainless steel – including concentrated acids, halogens, and ultra-pure fluids where even trace metal ion contamination is unacceptable.
Closure elements: The ball (in ball valves), disc (in check valves), plug (in plug valves), and strainer basket are also fully PFA-encapsulated or PFA-moulded, ensuring zero metal exposure at any flow-wetted surface.

Key PFA material properties:

Near-universal chemical resistance – resistant to almost all acids, alkalis, solvents, and oxidising agents at concentrations from dilute to concentrated
Operating temperature: −60°C to +180°C (liner); most Flowserve models rated to +150°C continuous process service
Extremely low surface energy (non-stick, anti-fouling) – media does not adhere to or contaminate the PFA surface
Electrically insulating – prevents galvanic corrosion and electrostatic product contamination
FDA-compliant grades available for pharmaceutical and food-contact applications

FERGO is an authorised Flowserve partner and stocks the complete Flowserve PFA valve programme under the renowned Atomac and Durco brand names. The range covers 5 valve types for a complete PFA pipeline system:

PFA Ball Valves – Quarter-turn shut-off; full-bore PFA-lined ball and body; ISO 5211 actuator interface for pneumatic or electric automation; flanged PN10/16 and ANSI Class 150; DN15–DN150. The most commonly specified PFA valve type for on/off isolation in aggressive chemical service.
PFA Check Valves – Wafer and flanged non-return valves with PFA-lined body and PFA disc; prevent backflow of aggressive or ultra-pure media without any metal contact; PN10/16, ANSI Class 150; DN15–DN300.
PFA Sight Glass – Flow observation windows with PFA-lined body and borosilicate glass sight window; visual process monitoring in aggressive chemical pipelines; flanged PN10/16; DN15–DN200.
PFA Plug Valves – Quarter-turn plug (cock) valves with PFA-lined conical plug and body; reliable shut-off with minimal dead volume; suitable for slurries, viscous fluids, and media where a full-bore straight passage is critical; flanged PN10/16; DN15–DN200.
PFA Strainers – Y-type and basket strainers with PFA-lined body and PFA-coated strainer basket; protect downstream equipment from particulates in aggressive media pipelines; flanged PN10/16; DN15–DN400.

Most models are available for immediate delivery from FERGO stock. For project quantities, special configurations, or sizes beyond the standard range, contact shop@fergo-valve.com or +49 21 31 / 15 39 28-0.

PFA offers near-universal chemical resistance – one of the broadest of any engineering material. This is the defining reason to specify PFA-lined valves over stainless steel or other alloys. Key media that PFA handles where stainless steel fails or is unsuitable:

Mineral acids (all concentrations):

Hydrochloric acid (HCl) – all concentrations; stainless steel corrodes severely above ~2% HCl; PFA is fully resistant
Sulphuric acid (H₂SO₄) – dilute to concentrated (including fuming); highly corrosive to SS at intermediate concentrations
Hydrofluoric acid (HF) – highly aggressive to glass, SS, and most metals; PFA is resistant at concentrations up to ~60% at moderate temperatures
Nitric acid (HNO₃) – dilute and concentrated; PFA resists even fuming nitric acid
Phosphoric acid (H₃PO₄) – all concentrations; routine PFA service

Alkalis and oxidising agents:

Sodium hydroxide / potassium hydroxide (NaOH / KOH) – concentrated caustic lyes; PFA is fully resistant
Chlorine (Cl₂), bromine (Br₂), fluorine (F₂) – gaseous and liquid halogens; among the most aggressive oxidising agents; PFA resists all three
Hydrogen peroxide (H₂O₂) – dilute to concentrated; PFA resistant; SS may be used at low concentrations but PFA is preferred for high-purity applications
Sodium hypochlorite (NaOCl) – bleach and chlorination chemicals; PFA fully resistant

Solvents and organic chemicals:

Aromatic solvents (toluene, xylene), ketones, esters, chlorinated solvents (DCM, TCE) – PFA resistant across the range
Dimethyl sulfoxide (DMSO), dimethylformamide (DMF) – aggressive solvents used in pharma/chemical synthesis; PFA resistant

Ultra-pure water and semiconductor process chemicals:

PFA is the liner material of choice for ultra-high-purity (UHP) water, piranha solution (H₂SO₄/H₂O₂), SC1/SC2 cleaning chemicals, and HF/HNO₃ etch solutions in semiconductor fabs – where even sub-ppb metal ion contamination from stainless steel is unacceptable

Important limits: PFA is not recommended for molten alkali metals, elemental fluorine at elevated temperatures, or certain fluorinated solvents above 150°C. Always verify the specific medium, concentration, and temperature combination against the Flowserve chemical resistance table or contact FERGO for application advice.

The choice between PFA-lined and stainless steel (or exotic alloy) valves depends on the medium, concentration, temperature, and purity requirements:

Choose a PFA-lined valve when:

The medium corrodes stainless steel: HCl above ~2%, concentrated H₂SO₄ at intermediate concentrations, HF at any concentration, Cl₂/Br₂ wet gas, or any medium shown as incompatible with SS 316 in chemical resistance tables
Metal contamination is unacceptable: Pharmaceutical APIs, UHP semiconductor chemicals, food-grade acids, and high-purity process streams where even ppb-level iron, chromium, or nickel contamination causes product failure or process excursions
Cost vs exotic alloys: Hastelloy C-276, titanium, or tantalum valves offer corrosion resistance comparable to PFA for some media, but at 5–15× the cost per valve. A GGG40 + PFA-lined valve covers the same chemical service at a fraction of the price.
Complete system consistency: When the pipeline is already PFA-lined, using PFA valves avoids introducing dissimilar materials at valve connections – maintaining lining continuity throughout the system
Operating temperature ≤ +180°C: Within the PFA liner's service range; for temperatures above +180°C, alternative materials must be evaluated

Choose stainless steel valves when:

The medium is compatible with SS 316 (1.4408) – water, steam, neutral process fluids, mild acids/alkalis at low concentration
Operating temperature exceeds +180°C – PFA liner is outside its service range; SS or carbon steel is required
High pressure rating (PN40 or above) is required – PFA-lined valves are rated to PN10/16 / ANSI Class 150; SS valves can reach PN40 and higher
Mechanically demanding service (abrasive slurries, high flow velocity causing liner erosion risk, or frequent actuation with high differential pressure) where liner integrity could be compromised over time

The Flowserve PFA valve range available from FERGO covers the following technical parameters:

Nominal sizes by valve type:

PFA Ball Valves: DN15 – DN150
PFA Check Valves: DN15 – DN300
PFA Sight Glass: DN15 – DN200
PFA Plug Valves: DN15 – DN200
PFA Strainers: DN15 – DN400

Pressure ratings:

PN10 / PN16 – flanged per EN 1092-1, compatible with DIN PN10/16 pipeline flanges throughout
ANSI Class 150 – flanged per ASME B16.5, for projects with American pipe specifications or export installations requiring ANSI flanging

Temperature rating: −60°C to +180°C (PFA liner); most Flowserve application data rates continuous process service to +150°C to maintain liner integrity over long service life.

Connection standard: Flanged face-to-face per EN 558 / ASME B16.10 as applicable. Wafer (face-to-face) construction available for check valves and some sight glass models for compact installation between standard PN10/16 or ANSI 150 flanges.

Actuation (ball valves and plug valves): ISO 5211 actuator mounting pad integral to the valve body allows direct mounting of pneumatic or electric part-turn actuators – same interface as standard stainless steel ball valves. FERGO can supply complete actuated PFA valve assemblies with pneumatic actuator, NAMUR solenoid valve, and limit switch box.

PFA valves are the standard valve solution in any process where the medium is incompatible with metallic wetted surfaces. Key industries:

Chemical manufacturing: Chlor-alkali plants (Cl₂, NaOH, HCl); sulphuric acid production and handling; hydrofluoric acid (HF) processes; nitric acid, phosphoric acid, and mixed acid systems; bleaching agents (NaOCl, H₂O₂); aggressive organic synthesis solvents. PFA valves replace Hastelloy, tantalum, or rubber-lined valves in these services at significantly lower cost.
Semiconductor and electronics manufacturing: UHP (ultra-high purity) chemical distribution systems; wet bench etch processes (HF/HNO₃, buffered oxide etch, piranha solution); SC1/SC2 wafer cleaning chemicals; photolithography chemical supply. PFA is the dominant lining material in semiconductor fabs because it introduces zero metal ion contamination into process chemicals.
Pharmaceutical and fine chemicals: API synthesis and handling involving aggressive solvents or acids; highly corrosive intermediate streams; sterile process lines where FDA-compliant PFA grades eliminate metallic contamination risk. PFA sight glasses provide visual monitoring without stainless steel contact.
Water treatment and environmental: Chlorination and fluoridation chemical dosing (Cl₂, NaOCl, HF); acid/alkali pH correction dosing (H₂SO₄, HCl, NaOH); reverse osmosis chemical cleaning systems; industrial effluent neutralisation.
Food and beverage: Acid cleaning-in-place (CIP) circuits; citric acid, phosphoric acid, and caustic soda (NaOH) handling; FDA-compliant PFA grades for direct food-contact applications where SS passivation is insufficient.
Pulp and paper: Bleaching chemical circuits (ClO₂, H₂O₂, NaOCl); acid washing; aggressive bleach plant chemical handling where PFA replaces titanium or rubber-lined equipment.

Yes – PFA ball valves and PFA plug valves from the Flowserve Atomac/Durco range are designed with an ISO 5211 actuator mounting pad integrated directly into the valve body (or top flange). This is the same standardised interface used on conventional stainless steel ball valves, which means:

Direct mounting of standard pneumatic or electric part-turn actuators without brackets or adapters
Full compatibility with FERGO's pneumatic actuators (double-acting and spring-return / fail-safe) and J4C electric part-turn actuators
NAMUR solenoid valve interface for pneumatic control from a DCS or PLC via NAMUR solenoid valves
Position feedback via limit switch box or inductive sensors
ATEX-certified actuator options for installation in explosive atmosphere zones (Zone 1 / Zone 2) – relevant for chemical plants handling flammable solvents alongside corrosive media

Typical automated PFA valve application: A PFA ball valve with spring-return pneumatic actuator (fail-closed / NC) and NAMUR 5/2-way solenoid valve provides safe emergency shutdown of an HCl or H₂SO₄ dosing line, closing automatically on air supply failure or control signal loss.

FERGO supplies complete actuated PFA valve assemblies – valve + actuator + solenoid + limit switch – factory-assembled, tested, and ready to install. Contact shop@fergo-valve.com for project configurations.

Flowserve is one of the world's largest and most established industrial valve manufacturers, with a dedicated PFA-lined valve programme under two specialist brands:

Atomac – Flowserve's European PFA valve brand, engineered and manufactured for demanding chemical process applications. The Atomac range covers PFA ball valves, check valves, sight glasses, plug valves, and strainers to EN / DIN standards (PN10/16, EN 1092-1 flanges).
Durco – Flowserve's internationally recognised PFA and lined valve brand with ANSI/ASME-standard products (Class 150, ASME B16.5 flanges) for global export projects and US-specification installations.

Both brands are built to the same Flowserve quality standards: extensive chemical resistance documentation, traceable material certification, dimensional compliance with international standards, and proven field reliability across the chemical, pharmaceutical, and semiconductor industries.

Why source PFA valves from FERGO?

Authorised Flowserve partner: FERGO is an authorised distributor of Flowserve PFA valves – all products are genuine Atomac/Durco with full manufacturer documentation and traceability
Stock availability: Most standard PFA valve models and sizes are held in FERGO stock for immediate or next-day delivery – critical for unplanned maintenance and production shutdowns
Complete system supply: FERGO supplies PFA valves alongside actuators, PTFE flange gaskets, solenoid valves, and all ancillary equipment needed for a complete PFA pipeline installation
Technical application support: 20+ years of industrial valve experience; expert guidance on media compatibility, size selection, and actuator specification for aggressive chemical service

Contact FERGO: shop@fergo-valve.com | +49 21 31 / 15 39 28-0 | Mon–Fri 8:00–17:00

Flowserve PFA Sight Glasses: Reliable Flow Monitoring for Aggressive Media