Industriële ventielen volgens API · ASME · DIN · EN
Veiligheidskranen met Piloot
Piloot-bediende veiligheidskranen paren een hoofdklep met een externe piloot: de piloot voelt de lijndruk en bedient de hoofdklep, wat volledige lift bij steldruk geeft met korte blowdown terwijl hij eronder dynamisch strak blijft — zodat de bedrijfsdruk dicht bij de steldruk kan draaien zonder simmer of mediaverlies. Typische klasse-dekking loopt DN25-DN200 (1" x 2" tot 8" x 10" inlet x uitlaat) bij ANSI Class 150-600 / PN16-PN100 in WCB-, CF8- of CF8M-bodies; het steldrukvenster wordt bij de RFQ tegen vereiste capaciteit en pilootselectie bevestigd. Piloten zijn pop-actie of modulerend en in het veld selecteerbaar; modulerende types tolereren hogere superimposed tegendruk. Geflenste (RF) einden. De pilootarchitectuur is wat de marges koopt: met een dome-oppervlakte groter dan de zittingsoppervlakte blijft de hoofdklep strak tot binnen 5% van de steldruk (98% zittingsdichtheid) waar veerkleppen al simmeren, pop-actie-piloten openen bij circa 1% overpressure en zetten terug op 97% (instelbaar tot 85%, blowdown -3% tot -15%), modulerende piloten volgen de vraag en bereiken volledige lift op 110% van de stelling, en tegendruk tot 70% — uitzonderlijk 95% — wordt gecompenseerd met een terugstroombeveiliging. De bepalende faalmodus is de piloot-sensielijning: deeltjes-houdende of kristalliserende media verstoppen zijn circa 10 mm boor (houd de klep op schone dienst, let op coking en polymerisatie), en een snelle opstarthelling kan het dome ontregelen en een vals lift tonen. Installatie houdt de afgelegen meetneming op 3/8-inch equivalent oppervlakte tot 100 voet zonder blokkeerklep in de toevoerlijn, en de veldtestverbinding laat functionele test in dienst toe. ASME VIII UG-126(b) vereist dat de piloot zelfbedienend is en de hoofdklep faalt-open bij volledige capaciteit. De selectie hangt af van de bedrijfs-versus-steldruk-verhouding, tegendruk, medium en pilootactie.
Onderdeel van de Veiligheidskranen familie
Laatst bijgewerkt: 2026-11
Familiespecificaties
| Pressure class / nominal rating designation | ANSI Class 150-600 / PN16-PN100 |
|---|---|
| Nominal valve connection size | DN25-DN200 (1in x 2in - 8in x 10in inlet x outlet) |
| Valve body material | WCB, CF8, CF8M |
| End connection types | flange (RF) |
| Service temperature range | -162 to 320°C |
| pilot type | pop-action or modulating; field-selectable |
| design note | main valve + external pilot; full-lift at set pressure with short blowdown |
| operating pressure ratio vs spring limit | Spring-loaded valves struggle to close completely above roughly 90% of set pressure; the pilot-operated main valve closes with a dome area larger than the seat area so closing force exceeds opening force, letting system operating pressure run within 5% of set pressure without increased seat leakage - the standard choice for high operating-to-set ratios |
| pop action reseat and adjustable blowdown | Pop-action pilot: opens at about 1% overpressure, closes at 97% of set pressure adjustable down to 85%, with blowdown adjustable between -3% and -15% above the API standard; modulated-closure pilots hold blowdown to max 7% |
| modulating vs pop pilot principle | Pop-action fully empties the main-valve dome for snap full lift; in modulate action the dome is only partially emptied, with the extent of emptying determined by the inlet pressure, so the main valve modulates with the relief demand |
| modulating partial opening capacity control | Modulating diaphragm-pilot execution: the valve opens further as process pressure rises and reaches full lift at 110% of set (High Gain option by 105%); the pilot is the nonflowing type - with the main valve relieving at steady pressure, no process fluid flows through the pilot |
| back pressure tolerance | Pilot actuation is differential, so back-pressure tolerance is high: pilot-operated safety valves can consistently compensate 70% back pressure and in certain cases run at a 95% back-pressure ratio; operability stays unaffected up to 70% of set pressure provided a backflow preventer is used whenever back pressure can exceed inlet pressure |
| seat tightness high operating ratio | Pilot-operated SRVs can achieve seat tightness up to 98% of set pressure for both the main valve and the pilot valve - the basis for running close to set pressure without simmer |
| posv definition | A pilot-operated safety relief valve is a pressure relief valve in which the major relieving device (main valve) is combined with and controlled by a self-actuated auxiliary pressure relief valve called a pilot valve |
| asme ug 126b pilot requirements | ASME Code Sec. VIII UG-126(b) permits pilot-operated pressure relief valves provided the pilot is self-actuated and the main valve opens automatically at not over set pressure and discharges full rated capacity even if some essential part of the pilot fails - the fail-open requirement |
| pilot blowdown short adjustment | The pilot portion of some pilot-operated valves can be set at blowdowns as short as 2% - far tighter than direct-spring pop valves |
| sensing line blockage failure mode | The pilot sensing (pressure-tap) line is the governing failure mode: media containing particles or prone to crystallization can plug the roughly ten-millimeter line, after which the safety valve can no longer perform its intended function; pilot-operated valves are supplied with filters and generally recommended for relatively clean service |
| dirty service limits | Pilot-operated valves should not be employed in abrasive or dirty service, where coking, polymerization or corrosion of wetted pilot parts can occur, or where the lading fluid can freeze or condense at ambient temperature; for severe dirty service where interconnecting tubing can clog, a pilot-operated SRV might not be the best fit |
| rapid pressure ramp false lift | During plant start-up with an extremely rapid system-pressure ramp rate, the dome area may not equalize with the same inlet pressure, resulting in insufficient closing force - a pilot-operated-specific false-lift mode |
| soft seal and temperature limits pilot | Pilot soft seals (O-rings) bound the application envelope: at temperatures of 200 °C and above the safety valve manufacturer should be consulted |
| sensing line remote pickup sizing rules | Installation rule for remote pressure pickup: piping must have the equivalent flow area of 3/8 in tubing for lengths up to 100 feet, longer runs require factory consultation; a block valve in the remote pilot supply line is not recommended and, if used, must be opened before pressurizing the main valve |
| field test connection in service | A field test connection allows operators to functionally test the pilot-operated SRV while it remains in service - a maintenance advantage over direct spring valves that must be pulled for bench testing |
| oem maintenance resources posv toolbox | OEM maintenance reference: the valve manufacturer publishes a dedicated maintenance toolbox for pilot-operated types 811 (pop action) and 821 (modulating) with repair guidance to the manufacturer quality standards |
| set pressure range example diaphragm pilot | OEM example envelope (pilot-operated relief valve with diaphragm pilot): set pressure range 15 psig to 740 psig; reseat pressure defined as the supply pressure where the dome pressure increases to 75% of supply pressure - an industry-reference anchor, not a tenant supply claim |
| Source 1 — orifice area range | effective orifice areas of 0.128 through 45.664 inches |
| Source 1 — inlet size range | valve inlet sizes 1-inch through 8-inch |
| Source 1 — Set-pressure range | set pressures from 15 to 3,705 psig (1 to 260 barg) |
| Source 1 — continuous temperature range | Continuous service temperatures from -50°F to +450°F |
| Source 1 — nonflowing pilot principle | with the non-flowing pilot provides highly reliable system overpressure protection |
| Source 1 — dirty service pilot design | The pilot is a non-flowing design minimizing the entry of dirt and the accumulation of hydrates |
| Source 1 — pilot supply filtration | Inline tubing external filter is also available |
| Source 1 — vertical pilot mounting | Consistent set pressure and blowdown are assured compared to horizontally mounted pilots that are erratic |
| Source 1 — orifice nozzle replacement | The orifice size may be changed by replacing a single component |
| Source 1 — external blowdown adjustment | Adjustable blowdown is external, reducing time and cost-consuming expenditures of valve removal |
| Source 1 — replaceable soft seat | With a replaceable soft seat, expensive parts and time-consuming lapping of metal seats are no longer necessary |
| Source 1 — asme capacity verification | capacity is assured by an independent third party, the ASME National Board Laboratory in Columbus, Ohio |
| Source 1 — operating ratio capability | The valve can be set within 5% of system operating pressure allowing the process to be maintained at close tolerance without valve leakage |
| Source 1 — typical applications | for Gas Compressors, Pressure Vessels, Cold Box Storage, Meter Runs, Gas Plants, Pipelines, and Transmission Stations |
| Source 2 — low pressure vacuum protection | provide safe, dependable, and accurate low pressure and/or vacuum protection |
| Source 2 — api2000 sealing | Seals in accordance with API 2000 requirements for Pilot Operated Relief Valves |
| Source 2 — rated flow overpressure | Rated flow at 10% overpressure provides the ability to operate closer to the tank MAWP, increasing the operating range of the process |
| Source 2 — seat action flexibility | Flexibility in terms of film or o-ring seat and snap or modulating action allows product customization to specific application requirements |
| Source 2 — vacuum breaker variant | The Model 1662A incorporates a vacuum breaker. |
| Source 2 — Nominal valve connection size | Sizes: 2” through 12” (50-300mm) |
| Source 2 — pressure settings | Pressure Settings: from 7.0* InWC to 15 psig |
| Source 2 — vacuum settings | Vacuum Settings: 7.0 InWC to 12 psig |
| Source 2 — standard body materials | Standard Body Materials: Carbon Steel (WCB/CS), Stainless Steel (CF8M/316), Aluminum (356) |
| Source 2 — supply media temperature range | Supply Media Temperature Range: -320° F to 300° F |
| Source 2 — drilling classes | 150# ANSI, PN10, PN16, JIS drilling classes available |
| Source 2 — pilot accessories | Pilot exhaust piped to discharge header, Field test connection, Manual blow down, Conical film seat pallet, Remote sense pickup, Pilot supply filter |
| Source 3 — Nominal valve connection size | Size 1/2” to 20” |
| Source 3 — Pressure Rating | Pressure Rating 150# x 150# to 2500# x 300# |
| Source 3 — End connection types | End Connection Flange End, Screwed End, Tri-Clover End |
| Source 3 — seat options | Seat Metal Seat / Soft Seat |
| Source 3 — orifice standard | Orifice As per API 520 |
| Source 3 — blowdown and overpressure | Blow Down <10% of Set Pressure, Over Pressure >10% of Set Pressure |
| Source 3 — Valve body material | Material Carbon steel, Stainless steel, Duplex-SS, nickel-molybdenum alloy, Alloy-20, nickel-copper alloy |
| Source 3 — pilot sensing design | Design - High Pressure, Semi- Nozzle/ Full- Nozzle, Piston Sensing Pilot |
| Source 3 — type options | Type Conventional, Balanced Bellow, Balance Piston, Pilot Operated, PTFE Lined |
| Source 4 — seat design options | Soft seat design: Provides repeatable bubble-tight performance before and after each relief cycle, Metal-to-metal seat design: Provides pilot valve performance in high temperature service |
| Source 4 — balanced design principle | Balanced design: Lift unaffected by back pressure; no expensive and fragile bellows required to balance against high back pressure |
| Source 4 — full lift dot maop capability | Full lift at set pressure: No overpressure required for full lift; allows D.O.T. installation to be set higher than Maximum Allowable Operating Pressure (MAOP) when pop action is used |
| Source 4 — replaceable seats and seals | Replaceable soft seats and seals: All seats and seals are renewable easily and quickly; no expensive, time-consuming seat lapping required |
| Source 4 — api526 center to face dimensions | API 526 direct spring center-to-face dimensions available for Series 200, 400, 500 and 800 pilots eliminating the need for piping modifications during upgrades |
| Source 4 — pop action cryogenic benefit | Pop action available: No main valve throttling, which helps prevent freeze-ups in cryogenic or refrigerant type services |
| Source 4 — modulating action benefits | Modulating action available: Significantly cut product loss per relief situation; reduce environmental pollution; avoid oversizing consequences; not as sensitive to inlet pressure losses as pop action |
Omvang & bronnotities
| back pressure capability tension | Back-pressure capability tension: the page spec states superimposed back pressure up to ~50% of set, while OEM documents state 70% consistent compensation (LESER, 95% in certain cases; Crosby 70% with backflow preventer); the ~50% figure should be owner-reviewed against per-configuration OEM limits. |
|---|---|
| pilot closure figures | Generic vendor pages describe pilot closure near 90% of set pressure; OEM pop-action figures are 97% (adjustable to 85%, blowdown -3% to -15%) - the OEM figures govern; generic-website numbers were excluded from this page. |
| set pressure envelope | Emerson Series 400 shows a 15-740 psig (about 1-51 barg) set-pressure envelope, so the page 0.1-10 MPa range is a tenant selection, not an industry ceiling; temperature envelope (-162 to 320 °C) sits against soft-seal limits where the manufacturer must be consulted at 200 °C and above - quote per configuration. |
Bestelling & documentatie
Documenten
Vraag de benodigde documentatieset mee aan bij de aanvraag — gebruikelijke items voor deze uitvoering (materiaalcertificaten, testrapporten volgens de genoemde inspectienorm, maattekeningen) worden in de offerte bevestigd en meegestuurd.
Offerte
Een offerteklare aanvraag noemt: nominale maat en drukklasse, voorkeur voor huis- en zittingsmateriaal, aansluiting, bediening, en het medium met temperatuur. Typische waarden op deze pagina zijn benchmarkreferentiebereiken; de bindende waarden worden in de offerte bevestigd.
Sample & levering
Leveringsvoorwaarden, orderhoeveelheden en levertijd worden per order afgesproken — noem het bestemmingsland en het gewenste schema bij de aanvraag.
Opslag & verzending
Bewaar ventielen met zittingen en afdichtingen beschermd tegen UV, ozon en vervorming, houd de vlakbeschermers op de aansluitvlakken tot installatie, en vermijd bij uitvoeringen met elastomeer- of PTFE-zittingen langdurige buitenopslag — zittingscompounden verouderen het snelst in direct zonlicht en bij vorst.
Veelgestelde vragen
Wat moet een offerteaanvraag voor veiligheidskranen met piloot bevatten?
De geldende norm en klasse, de nominale maat, de body- en zittingmaterialen, het medium met temperatuur en de bestemming — ontbrekende informatie wordt tijdens de offerte bevestigd.
Welke maat en drukklasse zijn er beschikbaar bij veiligheidskranen met piloot?
Een geverifieerd maat en drukklasse-bereik voor deze klep is nog niet op deze pagina gepubliceerd — het maat en drukklasse dat voor uw toepassing geldt, wordt voorgesteld en bevestigd tijdens de offerte. Stuur de bedrijfsomstandigheden mee met de aanvraag; de selectie wordt in het aanbod vermeld.
Welke bodymateriaal zijn er beschikbaar bij veiligheidskranen met piloot?
Een geverifieerd bodymateriaal-bereik voor deze klep is nog niet op deze pagina gepubliceerd — het bodymateriaal dat voor uw toepassing geldt, wordt voorgesteld en bevestigd tijdens de offerte. Stuur de bedrijfsomstandigheden mee met de aanvraag; de selectie wordt in het aanbod vermeld.
Kennis: selectiegidsen
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Specificaties bekijken →Offerte aanvragen voor Veiligheidskranen met Piloot
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Een grotere of niet-standaard eis voorbereiden? De Veiligheidskranen met Piloot-offertegids legt uit wat u moet meesturen, welke standaardbereiken en opties er zijn en welke documenten u kunt bijvoegen.
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