WIKA vs Ashcroft Pressure Gauge: Brand Comparison for Singapore Process Plants

WIKA: the global market leader

WIKA Alexander Wiegand SE & Co. KG, founded in 1946 in Germany, is by most measures the world's largest manufacturer of pressure and temperature measurement instruments. WIKA's pressure gauge range is extraordinarily wide, from simple utility gauges to EN 837-1 Class 0.6 precision gauges, with wetted material options spanning 316L stainless steel, Hastelloy, Monel, titanium, and PTFE-lined designs. In Singapore, WIKA has a direct office with local stock and application engineers, making it the practical default for process plant gauge specification where local support and fast replacement are valued.

WIKA's process gauge lineup includes the Model 213 and 232 (general service), Model 233 (safety pattern for high-pressure gas), and the 111.x precision gauge range (Class 0.6 for reference and calibration use). WIKA's Instrument Selection Tool and local technical team support specification for unusual process conditions. High-pressure, high-temperature, corrosive media, or SIL-rated applications where a detailed data sheet and application guidance are needed before ordering.

Ashcroft: heritage in Bourdon tube design

Ashcroft, founded in Connecticut in 1851, is often cited as the inventor of the commercial Bourdon tube pressure gauge. Acquired by HEICO Corporation and operating as a standalone brand, Ashcroft's gauges are standard specification in many American-designed process plants. Making them commonly found in Singapore facilities that were engineered by US firms or that follow American process design standards (ASME, ANSI). The Ashcroft Type 1008S and 1009 duragauge ranges are well-regarded for durability in demanding service conditions, and Ashcroft's 1109B pulsation dampened gauges are a preferred choice for pulsating service on pumps and compressors.

Ashcroft's local Singapore presence is through regional distributors rather than a direct office. This affects lead times for non-standard specifications and the speed of technical support for unusual applications. For standard gauges in common ranges and materials, availability through Singapore distributors is generally adequate.

What pressure gauge calibration checks

Pressure gauge calibration applies known reference pressures at multiple test points across the gauge's range and records the deviation between the gauge's reading and the reference. The standard test points are five: 0%, 25%, 50%, 75%, and 100% of the gauge's full scale. The certificate records:

• Applied reference pressure at each test point, from a traceable source (dead-weight tester, digital pressure comparator, or calibrated precision gauge)
• Gauge reading at each test point (ascending and descending, to detect hysteresis)
• Deviation from nominal in both absolute (kPa, bar) and percentage of full scale terms
• Hysteresis. The difference in gauge reading between the ascending and descending passes at the same pressure
• Expanded measurement uncertainty of the calibration

The calibration result is assessed against the gauge's EN 837-1 accuracy class specification. For a Class 1.0 gauge, the maximum allowable deviation at any test point is ±1.0% of full scale. If the gauge fails this criterion, it is adjusted (zero adjustment only on most Bourdon tube designs), quarantined, or replaced.

EN 837-1 vs ASME B40.100: the standards difference between WIKA and Ashcroft

One practical consideration for Singapore process plants is the standards basis of gauge accuracy specifications. WIKA gauges are typically specified to EN 837-1 (the European standard for Bourdon tube pressure gauges), while Ashcroft gauges are often specified to ASME B40.100 (the American standard). Both define accuracy classes, but with different class designations, en 837-1 Class 1.0 (±1.0% FS) corresponds approximately to ASME Grade 2A (±1.0% of span). When specifying a replacement or calibration interval for a mixed-brand fleet, confirm which standard applies to each gauge to ensure the acceptance criteria in your calibration procedure is correctly applied.

For SAC-SINGLAS accredited calibration, Unitest calibrates gauges to the applicable standard (EN 837-1 or ASME B40.100) and states the acceptance criterion on the certificate, so your quality records are unambiguous.

Safety pattern gauges and solid-front construction

For high-pressure gas service or applications where a Bourdon tube rupture could eject the movement or dial glass toward the operator, both WIKA and Ashcroft offer safety pattern (solid-front, blow-out-back) gauge designs. WIKA's Model 233.30 and 233.34 and Ashcroft's Type 1379 and 1982 safety pattern ranges use a solid case wall between the measuring element and the dial, so any Bourdon tube failure vents pressure out the back of the case rather than through the front glass. Singapore's workplace safety regulations, enforced by MOM, expect this design consideration on high-pressure gas and steam applications where a gauge failure could present a personnel hazard, and specifying a safety pattern gauge is standard practice on Jurong Island process units handling pressures above roughly 25 bar or on any pulsating high-pressure gas line. Neither brand holds an advantage in this category; both meet the relevant EN 837-1 or ASME B40.100 safety design provisions, so the decision again comes down to existing plant standardisation and specific model availability.

Diaphragm seals for corrosive, viscous, or particulate-laden media

Where the process media would damage a Bourdon tube directly, through corrosion, crystallisation, high viscosity, or suspended solids, both brands offer diaphragm seal assemblies that isolate the gauge's wetted parts from the process fluid using an inert fill fluid and a flexible diaphragm. WIKA's chemical seal range (Type 990 series) and Ashcroft's Type 1130 and 1132 diaphragm seals serve the same purpose: protecting the measuring element while transmitting pressure accurately through the fill fluid. The critical specification decision here is less about brand and more about diaphragm material compatibility with your specific process media (Hastelloy, tantalum, PTFE-coated, and various elastomer options exist for a reason) and correctly sizing the fill fluid volume and diaphragm area for your pressure range, since an undersized diaphragm assembly introduces its own measurement lag and reduced accuracy. Both manufacturers' Singapore-facing technical teams (WIKA directly, Ashcroft through its distributor network) can advise on media compatibility, and getting this specification wrong is a far more common source of field problems than any brand-level accuracy difference.

Analog versus digital pressure gauges

Both WIKA and Ashcroft also produce digital pressure gauge and pressure indicator ranges as an alternative to traditional Bourdon tube analog designs. Digital gauges typically offer tighter accuracy classes (0.1-0.25% FS is achievable in a digital indicator where it would be unusual in a mechanical gauge), a digital display that removes parallax reading error, and often a local data logging or 4-20mA output option that a purely mechanical gauge cannot provide. The trade-off is battery dependency, generally higher unit cost, and, in some designs, a more complex failure mode that a maintenance technician cannot diagnose by eye the way a bent Bourdon tube or stuck pointer is visually obvious. For most Singapore process plant applications where a local visual indication is the primary requirement, mechanical Bourdon tube gauges from either brand remain the practical default; digital gauges earn their premium in applications specifically needing tighter accuracy, data logging, or remote monitoring integration.

Common field failure modes and what they mean for calibration planning

Across both brands, the most common failure mode we see at calibration is a stuck or sluggish pointer caused by internal corrosion or contamination of the movement, typically from a gauge specified without liquid filling being subjected to sustained vibration or pulsation it was not designed for. The second most common is zero drift from repeated over-pressure events, where the process occasionally spikes beyond the gauge's rated range and permanently deforms the Bourdon tube slightly, producing a gauge that reads consistently low or high across its whole range rather than failing outright. Neither failure mode is unique to WIKA or Ashcroft; both are consequences of gauge specification not matching actual service conditions. This is precisely why as-found calibration data matters: a gauge trending toward zero drift across successive calibrations is telling you something about the process conditions it is actually experiencing, not just about the gauge itself, and is worth investigating rather than simply re-zeroing and moving on.

Dial size and readability: an easy-to-overlook practical factor

Both WIKA and Ashcroft offer the same standard dial sizes, commonly 63mm, 100mm, and 150mm, and the choice between them is a genuinely practical rather than technical decision that nonetheless affects how usefully the gauge functions in service. A 63mm gauge mounted at eye level on a compact skid is easy to read; the same size gauge mounted three metres up on a tall vessel, or viewed from several metres away on a walkway, becomes effectively unreadable without climbing closer, which in a process plant defeats much of the purpose of having a local visual indication at all. Larger 150mm dials, with correspondingly larger, more widely spaced scale markings, are the correct specification for any gauge mounted at height, at distance, or in low-light process areas, and this decision should be made based on the actual viewing distance and conditions at the installation location, not simply defaulted to whatever size was used on the last project. Both brands offer clear, high-contrast dial designs at each size, so this is a specification decision independent of brand choice, but one worth deliberately making rather than defaulting to a habitual size regardless of where the gauge will actually be read from.

Process connection standards: NPT, BSP, and getting the thread right

Both WIKA and Ashcroft manufacture gauges with a range of process connection thread standards, most commonly NPT (National Pipe Thread, the American standard) and BSP (British Standard Pipe, more common in installations following European or Commonwealth engineering conventions), and getting this specification wrong is a surprisingly common and entirely avoidable source of installation delay. NPT and BSP threads are not interchangeable despite superficially similar sizing nomenclature; forcing a mismatched thread can damage both the gauge's connection and the process fitting, and even where a fitting technically threads together, a mismatched standard frequently will not seal reliably under pressure. Singapore process plants, given the mix of American and European-influenced engineering standards across different EPC contractors and eras of plant construction, see a genuine mix of both standards in service, which makes confirming the existing connection standard at each specific tap point, rather than assuming plant-wide consistency, a necessary step before ordering a replacement gauge of either brand.

How liquid filling actually dampens vibration and pulsation

It is worth understanding the actual mechanism behind liquid-filled gauges, since it explains why this specification matters so much in certain services and not others. A liquid-filled gauge has its internal movement submerged in glycerine, silicone oil, or a similar fluid, and this fluid physically damps the mechanical oscillation of the pointer and internal linkage that would otherwise occur when the gauge is subjected to vibration (from an adjacent pump or compressor) or pulsation (from reciprocating equipment creating rapid pressure fluctuations in the line). Without this damping, the pointer visibly vibrates or oscillates rapidly, making the gauge difficult to read accurately and, more importantly, subjecting the internal Bourdon tube and movement to accelerated mechanical fatigue that shortens the gauge's accurate service life considerably faster than the same gauge would experience in a stable, non-pulsating application. Both WIKA and Ashcroft offer glycerine and silicone fill options across their process gauge ranges, with silicone generally preferred for wider temperature range tolerance and glycerine remaining a lower-cost standard option for moderate temperature applications; neither brand holds a meaningful advantage in fill fluid performance, and the decision to specify liquid filling at all, based on the actual vibration or pulsation profile of the installation, matters considerably more than which brand's fill fluid is used.

Case wall material and corrosion resistance in Singapore's coastal, humid environment

Beyond the wetted parts discussed for aggressive media, the gauge's external case material matters more in Singapore's climate than it does in drier, more temperate installations, given the combination of high ambient humidity, coastal salt exposure for plants near Jurong Island's waterfront, and frequent washdown in food and pharmaceutical facilities. Both WIKA and Ashcroft offer stainless steel case options across their process gauge ranges, and specifying stainless steel over a painted carbon steel case, even where the process media itself does not require it, is a worthwhile upgrade for any gauge in an outdoor, coastal, or frequently washed-down location, since a corroding case, even if it does not affect the gauge's internal measuring accuracy, degrades the window seal integrity over time and can eventually allow moisture ingress into the movement itself. This is a genuinely practical, climate-specific specification consideration that applies equally to both brands and is worth raising explicitly with either manufacturer's local technical team when specifying gauges for outdoor or washdown-prone locations rather than defaulting to whatever case material happens to be the standard catalogue option.

Traceability and calibration: the step both brands share equally

Regardless of which brand is specified, every pressure gauge feeding a quality-affecting or compliance-relevant measurement must ultimately carry a traceable calibration, following the same principles covered throughout this Knowledge Hub. A new WIKA or Ashcroft gauge arrives with a factory test certificate confirming it left the manufacturer within specification, but this factory certificate is not a substitute for accredited calibration once the gauge enters service, since it documents a one-time factory condition rather than an ongoing, periodically verified traceability chain. Once installed, both brands are calibrated using the identical accredited process, dead-weight testers or pressure comparators applying known reference pressures traceable to Singapore's National Metrology Centre, and the resulting certificate carries the same evidentiary weight regardless of the gauge's brand. This is worth stating plainly because procurement teams sometimes assume a premium brand name substitutes for genuine ongoing calibration diligence; it does not, and a WIKA or Ashcroft gauge left uncalibrated past its due date carries exactly the same unverified-accuracy risk as any other brand in the same situation.

A practical specification checklist

When specifying a replacement or new pressure gauge, regardless of brand, confirm: the required accuracy class against your process tolerance (applying the 4:1 test-to-tolerance principle); the correct pressure range, sized so normal operating pressure sits in the middle third of the gauge's scale rather than near either extreme; the wetted material compatibility with your process media, including whether a diaphragm seal is needed; whether liquid filling is required for vibration or pulsation damping; whether a safety pattern (solid-front) design is required for the pressure and media involved; the process connection size and thread standard (NPT or BSP) to match your existing fittings, confirmed at the specific tap point rather than assumed plant-wide; the case material appropriate to the installation's exposure to humidity, corrosion, or washdown; and the dial size appropriate to the gauge's actual viewing distance and mounting location. Getting these decisions right matters considerably more to gauge accuracy, readability, and service life than the brand name on the dial.