Brand: WIKA

WIKA 990.27 Diaphragm Seal

Name: WIKA 990.27 Diaphragm Seal – Datasheet & Price Quote
Brand: WIKA

Description

Overview

WIKA 990.27 is a diaphragm seal with flange connection engineered to protect pressure measuring instruments from aggressive, adhesive, crystallising, corrosive, highly viscous, or hot process media. Featuring a flange with a flush welded diaphragm, the WIKA 990.27 is mounted in place of a blind flange and is designed to fit all commonly used standard flanges, making it the preferred solution across chemical, petrochemical, and general process industries wherever the process medium itself would otherwise damage a direct-mount pressure gauge or transmitter.

With engineering support in Muscat, Seven Star LLC supplies the WIKA 990.27 diaphragm seal to chemical, petrochemical, and oil and gas customers across Oman and the wider GCC. Every unit supplied through Seven Star LLC comes with manufacturer documentation and access to local technical support – supporting facility engineers and procurement teams in Muscat, Sohar, and Salalah who specify the WIKA 990.27.

Working Principle

The WIKA 990.27 operates by physically isolating the pressure measuring instrument from the process medium. A flush-welded diaphragm, mounted flat against the flange face, contacts the process fluid directly, while the space behind the diaphragm and the connected instrument is filled with a system fill fluid. As process pressure acts on the diaphragm, it flexes slightly and transmits that pressure through the incompressible fill fluid to the pressure gauge, switch, or transmitter mounted on the seal, giving an accurate reading without the wetted internals of the measuring instrument ever contacting the aggressive process fluid.

This isolation principle gives the WIKA 990.27 its defining protective advantage: because the flush diaphragm design has no crevices, pockets, or dead spaces where product can collect, it resists clogging from highly viscous or crystallising media, and the diaphragm and sealing face can be manufactured from corrosion-resistant alloys selected specifically for the process fluid in question. Assembly to the measuring instrument can be made via a direct connection, through a cooling element for high-temperature media, or via a flexible capillary for remote-mounted instrumentation.

Engineering Design of the WIKA 990.27

The WIKA 990.27 is available in a wide variety of dimensions following common industry flange standards and nominal widths, and is suitable for all currently used standard flanges, so it can be installed in place of a blind flange without custom fabrication. The upper body and wetted parts (diaphragm and sealing face) can be manufactured from identical or different materials depending on the application, and the diaphragm and sealing face are also available with special coatings for additional chemical or abrasion resistance where a solid alloy alone is insufficient.

A cell-type design variant is also available for applications requiring a sandwich-flange configuration with a contoured diaphragm bed. System fill fluids are selected to match the process temperature range and the specific pressure instrument connected, and the diaphragm seal system as a whole can be configured for hazardous area installations per the relevant ATEX or IECEx documentation, giving engineers a fully certified, application-matched protective barrier between instrument and process.

Key Features

The WIKA 990.27 combines flexible material selection with a proven flush-diaphragm design that makes it a standard choice for protecting pressure instruments from difficult process media.

A flange with flush welded diaphragm eliminates dead spaces where crystallising or highly viscous media could otherwise collect.
Available for all commonly used standard flanges and nominal widths, allowing installation in place of a blind flange.
The upper body and wetted parts can be manufactured from identical or different materials to match specific chemical compatibility needs.
Optional diaphragm and sealing face coatings extend chemical and abrasion resistance beyond the base alloy.
Assembly options include direct connection, cooling element for high-temperature media, or flexible capillary for remote mounting.
A cell-type sandwich-flange variant with a contoured diaphragm bed is available for specialized installations.
System fill fluids are selected to match process temperature and the connected pressure instrument.
Suitable for hazardous area installations per applicable ATEX/IECEx documentation.

Industrial Applications

The WIKA 990.27 is deployed across the chemical process industry, petrochemical industry, and general process and machine building sectors wherever aggressive, highly viscous, crystallising, or hot media would otherwise damage an unprotected pressure gauge or transmitter. Typical duties include reactor and vessel pressure protection, slurry and polymer process lines, and high-temperature process pressure measurement requiring a cooling element.

Backed by manufacturer datasheet documentation, Seven Star LLC distributes the WIKA 990.27 to refineries, petrochemical complexes, and chemical processing facilities throughout Oman and the GCC. The diaphragm seal is a strong fit for process pressure protection across the Sohar and Salalah petrochemical zones, as well as for chemical and oil and gas facilities across Muscat that require dependable isolation of pressure instruments from harsh process media.

Technical Specifications

The table below summarizes the core specifications of the WIKA 990.27 diaphragm seal as supplied by Seven Star LLC.

Parameter	Specification
Model	WIKA 990.27
Type	Diaphragm seal with flange connection, flush diaphragm
Process Connection	All common standard flanges and nominal widths
Diaphragm Design	Flush welded, no dead spaces
Materials	Upper body and wetted parts, identical or different alloys per application
Optional Coatings	Diaphragm and sealing face coatings available
Assembly Options	Direct connection, cooling element, flexible capillary
Variant	Cell-type sandwich flange with contoured diaphragm bed available
Hazardous Area Suitability	ATEX / IECEx (per system documentation)
Typical Applications	Chemical, petrochemical, process industry, machine building

Request a Quote for WIKA 990.27 Diaphragm Seal

Seven Star LLC supports the full procurement cycle for the WIKA 990.27 diaphragm seal, from formal RFQ submission to confirmation of availability and lead time, technical datasheet delivery, and direct consultation with our instrumentation division on flange size, material selection, and fill fluid for your process application. Working closely with plant engineers in the region, we supply every WIKA 990.27 diaphragm seal with manufacturer documentation and dependable local technical support. Contact Seven Star LLC today to request a quotation or discuss your diaphragm seal requirements.

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About brand

WIKA is the German manufacturer of pressure, temperature, level and flow instruments, best known for its pressure gauges. Alexander Wiegand and Philipp Kachel founded it on 2 January 1946 in Klingenberg am Main, Bavaria. The name comes from the first two letters of their surnames. WIKA is still run by the Wiegand family and is headquartered in Klingenberg.

Seven Star LLC is an independent supplier in Muscat. We list WIKA pressure gauges, diaphragm seals, transmitters, switches, thermometers and thermowells, and supply them to plants, contractors and panel builders in Oman and the GCC by model and order code.

WIKA company profile

Established	2 January 1946, Klingenberg am Main, Germany, by Alexander Wiegand and Philipp Kachel
First products	Mechanical pressure and temperature gauges
Ownership	Family-owned; managed by Alexander Wiegand, grandson of the founder, since 1996
Product families	Pressure gauges, diaphragm seals, pressure transmitters and switches, thermometers, RTDs, thermocouples, thermowells, calibration equipment, level and flow instruments

Milestones

1946: Alexander Wiegand and Philipp Kachel found the company in Klingenberg am Main on 2 January; pressure gauge production starts at the end of the year. The name WIKA comes from the first letters of their surnames.
1951: Konrad Wiegand, the founder's son, takes over management.
1967: Ursula Wiegand leads the company after her husband's death.
1986: The company is reunited with the Kachel thermometer factory, which Philipp Kachel had set up after leaving in 1956.
1994: Certification to DIN ISO 9001.
1996: Alexander Wiegand, the founder's grandson, becomes head of the company.

WIKA products we list

Family	Models	Typical use
Bourdon tube pressure gauges	111.10, 111.12, 212.20, 213.53, 232.50, 233.50, 232.30/233.30 safety pattern	HVAC and utilities (111 series) to process plants (23x series in stainless steel)
Diaphragm and differential pressure gauges	432.50, 732.51, 700.01, DPGT43	Low pressures, viscous or dirty media, and filter differential pressure
Diaphragm seals	990.10, 990.27	Separating the gauge from corrosive, hot or clogging media
Transmitters, switches and test gauges	A-10, UPT-20, PSM01, CPG1500	4-20 mA pressure signals, switching, and precision calibration checks
Thermometers	TG54, Model 55, A52, 73 gas-actuated	Local temperature indication on pipes, vessels and HVAC
Temperature sensors and thermowells	TR10, TR12-B, TR33, TC10-B, TW10 flanged, TW15 threaded	RTD and thermocouple measurement in process lines

The WIKA model number tells you the build. In 232.50, the first digit 2 means stainless steel wetted parts, the second digit 3 means a liquid-fillable case, and ".50" is the case style. The 111 series uses copper alloy wetted parts and suits water and air. Where the medium is corrosive, very hot or would block the gauge, a diaphragm seal such as the 990.27 keeps it away from the Bourdon tube. For temperature, a thermowell like the TW10 lets you remove the sensor without opening the process.

Where WIKA instruments are used

In Oman and the GCC, WIKA gauges, transmitters and thermometers are used in oil and gas, refining and petrochemical plants, power and desalination, water networks, district cooling and HVAC, and on skids and machines from OEMs.

Ordering WIKA instruments: what we need

Send the model, dial size (for example 63, 100 or 160 mm), range and unit, connection size and position (lower or back mount), accuracy class and whether liquid filling is needed. For diaphragm seals and thermowells, add the process connection, materials and insertion length.

Facts checked against WIKA company history, October 2026.

Browse WIKA products by category: Pressure Instrumentation, Temperature Instrumentation.

Frequently Asked Questions

What is the purpose of the WIKA 990.27 diaphragm seal?

The WIKA 990.27 protects pressure measuring instruments from aggressive, adhesive, crystallising, corrosive, or highly viscous process media by physically isolating the instrument from the process fluid using a flush diaphragm and system fill fluid.

Can the WIKA 990.27 be installed on standard pipe flanges?

Yes. The 990.27 is designed to fit all commonly used standard flanges and nominal widths, and is mounted for pressure measurement in place of a blind flange, without requiring custom fabrication.

Does the flush diaphragm design help with viscous or crystallising media?

Yes. The flush welded diaphragm has no crevices or dead spaces where product can collect, which makes the 990.27 well suited to highly viscous or crystallising media that would otherwise clog a recessed-diaphragm seal design.

How is the WIKA 990.27 connected to the pressure instrument for high-temperature applications?

For high-temperature media, the diaphragm seal can be assembled to the measuring instrument via a cooling element, which protects the connected pressure gauge or transmitter from excessive heat, or alternatively via a flexible capillary for remote mounting.

Is Seven Star LLC an experienced supply partner for WIKA products?

Yes, Seven Star LLC is an experienced supplier of WIKA in Oman and the GCC. We supply genuine WIKA instrumentation with manufacturer documentation and local technical support.

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