Sanitary Temperature Transmitter for Food and Pharmaceutical CIP-SIP Lines: Hygienic Pt100 Monitoring

Sanitary Temperature Transmitter for Food & Pharmaceutical CIP/SIP Lines

In dairy, beverage and pharmaceutical plants, the temperature loop is not just a control point — it is a product-safety boundary. This field case documents a sanitary temperature transmitter deployment across fermentation tanks and a high-temperature short-time (HTST) pasteurisation loop, where cleanability, hygiene and repeatability decide whether a batch can be released or must be discarded.

Real Working Condition

The same utility serves two different hygienic duties:

• CIP cycle: caustic and hot-water rinse at roughly 75–85 °C, alternating with acid wash.
• SIP cycle: saturated steam sterilisation at 121 °C, with short 134 °C excursions.
• Product side: viscous dairy media and buffered pharmaceutical solutions from 4 °C to 95 °C.

The wetted surface must be smooth, crevice-free and fully drainable. A conventional threaded thermowell creates a dead leg that traps product and cannot be validated in a hygienic zone.

Customer Pain Points

• Bacterial harbourage: the thread root of standard transmitters failed repeated swab testing.
• Zero drift: after hundreds of steam cycles, the loop reading skewed, forcing conservative over-hold and lost throughput.
• Documentation burden: IQ/OQ/PQ protocols demand traceable material and calibration records for every wetted part.

Engineering Selection

The plant standardised on the QW-SLS78 sanitary temperature transmitter with a Tri-Clamp connection, supported by the QW-SLS79 RTD food probe for in-line measurement. Both use a Pt100 class A element in 316L stainless steel with a polished wetted surface and food-grade seals.

Installation Logic

• Flush diaphragm mounted at a self-draining angle so the pipeline empties completely after CIP.
• Minimum immersion length respected so the sensing tip sits in the bulk flow, not in the wall boundary layer.
• Positioned at least ten pipe diameters downstream of the last bend to avoid stratification error.
• Transmitter head kept above the pipe so condensate cannot pool on the electronics.

Results

With a flush hygienic connection and short immersion, the loop responds quickly to the CIP ramp-up while remaining fully cleanable. A typical loop accuracy of ±0.15 °C lets the batch-hold window be tightened without added risk, and validated material certificates simplify qualification.

Procurement Decision

Buyers should confirm hygienic certification (3-A / EHEDG where applicable), wetted-material certificates (EN 10204 3.1), seal elastomer compatibility with caustic and steam, the required Tri-Clamp size, and spare-part lead time. Minimum order quantity starts from one set for trial installation.