Technical information

Technical cleanliness of pointer measuring instrumentsof special versions
WIKA data sheet IN 00.58

Application area
This document describes manufacturing processes for
special versions that require a very high technical cleanlinessof the wetted parts.
This applies for mechanical and mechatronic pointermeasuring instruments with stainless steel materials(e.g. 316L) and special materials (e.g. Monel, Hastelloy).
Instrument

Model

Bourdon tube pressure gauge

1, 2, 3Absolute pressure gauge

5

Differential pressure gauge

7

Bimetal thermometer

TG53, TG54, 55

Diaphragm pressure gauge
Capsule pressure gauge

Mechatronic pressure gauge
Gas-actuated thermometer
Mechatronic thermometer

46PGS, DPGS, PGT, DPGT, APGT73

TGS55, TGS73, TGT73

Pointer measuring instruments with wetted parts from copper alloy (brass) and diaphragmseals are not considered in this technical information.

WIKA expertise
WIKA has decades of experience in the production ofpressure gauges and thermometers guarantees a high levelof cleanliness of the wetted parts. This is ensured, among
other things, by the use of standardised processes and thesupport of the WIKA expert group for technical cleanliness.
For the pressure gauge version “Oil- and grease-freefor oxygen”, WIKA confirms a hydrocarbon limit value of< 550 mg/m² for scale ranges ≤ 30 bar [≤ 400 psi] and< 220 mg/m² for scale ranges > 30 bar [> 400 psi], based on
periodically recurring tests (in line with ISO 15001:2012 andASTM G93 level D/E).

WIKA data sheet IN 00.58 ∙ 02/2024

Additional fundamental sampling tests (burn-out test when
exposed to oxygen pressure surges) at external test centres
confirm the basic suitability of the “Oil and grease-free foroxygen” version of pressure gauges for this medium.
These special versions, and the additional cleaning-related
manufacturing processes carried out for them, are described
below.

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Version: “Silicone-free”
Silicone-free or silicone oil-free means that all components in contact with the atmosphere must be largely free of silicone. Thisrequirement is often made for paint finishing systems (e.g. in the automotive industry). The smallest silicone residues can leadto painting defects (so-called silicone craters) and ruin the painting result.
However, for process and production reasons, it is not possible to provide general confirmation of the absence of paint wetting
impairment substances (freedom from PWIS) by selecting this version.
Cleaning steps in the production process■ If necessary, thorough hand cleaning before starting production, without the use of skin care products (hand cream)■ Regular cleanliness checks and, if necessary, cleaning of equipment (test and adjustment benches)■ Avoidance of assembly aids with silicone-containing, paint wetting impairment substances, where possible■ No storage of silicone or lubricating materials in the vicinity of the production process, where possible■ Selected models (e.g. diaphragm pressure gauges) receive separate cleaning and drying of selected parts and assemblies

before assembly (also for internal surfaces)■ 100% cleaning of the surrounding parts of the instrument before packaging■ Individual packaging in silicone-free, sealable or heat-sealed plastic bag

Marking “Silicone-free”

Version: “Oil- and grease-free”
The requirement for internal parts to be free of oil and grease is often made in the food and pharmaceutical industries. Thisrequirement also exists in other sectors such as industrial gases, water and wastewater, machine building and automation.
Cleaning steps in the production process■ Regular cleanliness checks and, if necessary, cleaning of equipment (test and adjustment benches)■ The instruments are primarily adjusted using oil- and grease-free, dry compressed air or nitrogen. For higher pressure

ranges, adjustment is only possible with water, followed by drying of all wetted parts in a vacuum oven.

■ Particularly thorough visual inspection of the surfaces before shipping

Marking “Oil- and grease-free”

WIKA data sheet IN 00.58 ∙ 02/2024

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Version: “Oil and grease-free for oxygen”
The use of oxygen is very versatile and widespread. The demands are extremely high due to the easy flammability and highexplosion risk of oxygen. Oil and grease are particularly dangerous in the presence of oxygen, as they can easily be an ignition
source and burn with explosive ferocity. This ignition source is not always obvious in piping systems. A fire can be causedby friction, high flow rates, heating due to turbulence or adiabatic compression. For example, gas with a high flow rate cansuddenly hit an obstacle, e.g. a closed valve. If pipe connections are contaminated with mineral oils or greases, oxidation
reactions with the carbon components can easily occur. The resulting high temperatures can then lead to spontaneous
combustion and trigger a chain reaction.
For oxygen applications, WIKA recommends the use of a restrictor in the process connection to reduce the rate of pressure
increase in the measuring system.
Applications of oxygen■ Breathing gas in medicine and aerospace■ Oxidising agents in combustion processes to achieve high temperatures■ Metallurgy, in pig iron and steel production and in copper refining■ Chemistry and biology

ư Olefin oxidation, partial oxidation of coal and heavy oilư Production of hydrogen and synthesis gas, sulphuric and nitric acid, acetylene■ Welding, cutting, separating, flame annealing■ Drinking water and wastewater treatment■ Semiconductor technology■ Fuel cells

Cleaning steps in the production process■ Regular cleanliness checks and, if necessary, cleaning of equipment (test and adjustment benches)■ The instruments are primarily adjusted using oil- and grease-free, dry compressed air or nitrogen. For higher pressure
ranges, only adjustment with water is possible. In this case, the entire measuring system is then dried in a vacuum oven.
■ Use of wetted materials, system fill fluids and casing fill fluids that are suitable or approved for use in conjunction withoxygen■ Before installation, the wetted parts are cleaned (e.g. in an ultrasonic bath) and then dried again. This also applies, inparticular, to internal surfaces.
■ After cleaning, internal transport is carried out in separately sealed and cleaned transport containers.
■ The instruments are largely handled with gloves, so as not to contaminate internal parts■ Particularly thorough visual inspection of the surfaces■ The process connection is usually sealed with a protective cap for shipping■ Instruments are packed in sealed plastic bags (sometimes with desiccant)Marking “Oil and grease-free for oxygen”

WIKA data sheet IN 00.58 ∙ 02/2024

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02/2024 EN© 11/2023 WIKA Alexander Wiegand SE & Co. KG, all rights reserved.
The information provided in this document corresponds to the current state of the art and may vary slightly depending on the production site.
The information provided is for general information purposes only and is not legally binding. We reserve the right to make changes in individual cases or special versions.
In the event of a different interpretation of the translated and the English data sheet, the English wording shall prevail.

WIKA data sheet IN 00.58 ∙ 02/2024

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WIKA Alexander Wiegand SE & Co. KG
Alexander-Wiegand-Straße 30
63911 Klingenberg/GermanyTel.
+49 9372 132-0
info@wika.dewww.wika.com