Sanitary Pressure Gauges: Why Standard Instruments Fail in Hygienic Processes

Pressure measurement is one of the most basic and ubiquitous measurements in any process plant. In non-critical applications, a standard bourdon tube gauge does the job. But in pharmaceutical production, biotech, dairy processing, and other hygienic industries, a standard gauge can become a contamination source — and a regulatory liability.

The Problem with Standard Gauges

A conventional pressure gauge typically connects to the process via a threaded socket or nipple. This creates a narrow dead space — a pocket of stagnant product that cannot be reached by cleaning fluids. Over time, bacteria colonise this space and potentially re-contaminate the process stream.

Additional issues with standard instruments in hygienic environments:

• Threaded connections create crevices that trap product residue
• Brass, carbon steel, and standard elastomers are not approved for food or pharma contact
• The bourdon tube mechanism cannot withstand CIP temperatures (up to 95 °C) or SIP conditions (121 °C, 2 bar)
• Gauge oil (glycerine filling) may leak into the process if the diaphragm fails

What Makes a Gauge Sanitary?

A truly sanitary pressure gauge addresses every one of these contamination pathways. The key design features are:

Flush-Mount Process Connection

Sanitary gauges use clamp (Tri-Clamp), DIN 11851, or Varivent connections that present a smooth, flush surface to the product. There is no dead leg, no thread, and no crevice. The measuring diaphragm sits flush with the pipe wall or vessel interior.

All-Stainless Wetted Parts

Wetted materials are typically 316L stainless steel with surface roughness ≤ 0.4 µm Ra (electropolished). Sealing elements use EPDM, FKM, or PTFE — all FDA and EC 1935/2004 compliant.

CIP and SIP Resistance

Sanitary gauges must withstand repeated thermal cycling: cold rinses, hot caustic washes (80–95 °C), acid rinses, and steam sterilisation at 121–134 °C. The diaphragm seal and housing are designed for these conditions without degradation or loss of accuracy.

Regulatory Requirements

• FDA 21 CFR: materials must be suitable for food and pharmaceutical contact
• EC 1935/2004: materials in contact with food must not transfer constituents in harmful quantities
• 3-A Sanitary Standards (14-02): requirements for pressure-sensing devices
• EHEDG guidelines: equipment design for hygienic processing
• ASME BPE: bioprocessing equipment standard, including surface finish and drainability

Gulbinat's Approach

Gulbinat, a German manufacturer within the Trinox group, has specialised in sanitary instrumentation for over 40 years. Their pressure gauge range is designed from the ground up for hygienic applications — not adapted from industrial models.

• Fully welded diaphragm seal with no O-ring in the product path
• Accuracy class 1.0 (EN 837-1) with optional class 0.6
• Process connections: Tri-Clamp, DIN 11851, Varivent, aseptic flange
• Temperature resistance up to 150 °C continuous
• Optional electrical output (4–20 mA) for process monitoring

As the exclusive Gulbinat partner in the Benelux, Tas & Company stocks a range of standard sizes and configurations for fast delivery. For non-standard requirements — unusual pressure ranges, special connections, or ATEX certification — we work directly with the Gulbinat engineering team in Germany.