• By Chris Dodds : estimated reading time 5 minutes

Rotronic have announced the introduction of a new series of Intrinsically Safe Sensors and Measurement Transmitters, suitable for installation in hazardous area locations where there is a risk of explosion due to the presence of explosive dusts or gases in the environment – this includes Zone 1 which is common to the oil, gas and petrochemical industries.

For safe area, non-ATEX certified locations in the offshore industry aluminium housed temperature and humidity measurement transmitters are available, please visit Rotronic Hygroflex 7.

Rotronic humidity and temperature sensors were initially developed for the food and beverage, pharmaceutical, biotechnology, grain, sugar, petrochemical, oil and gas industries.

Zone 1 and Zone 21 ATEX certified Rotronic sensors and instruments are suitable for hazardous area industries where potentially explosive atmospheres preclude the safe use of uncertified equipment.

Rotronic HygroFlex5-EX is available with a Zone 21 certified transmitter for potentially explosive dust atmospheres in the pharmaceutical and food/beverage industry.

Dust Explosion & Fire Caused By Sugar Dust – Imperial Sugar Refinery At Port Wentworth GA USA. US Chemical Safety & Hazard Investigation Board.

Not So sweet sugar…..

This is a true story.

The floors of the Imperial Sugar Company’s plant buckled and the walls were blasted out.

The damage caused the electricity to be cut off from most of the plant, making escape and fire suppression difficult. The fire raged for hours.

By morning, the full extent of the devastation was clear. Thirteen people dead and 40 injured. The plant, which is the largest sugar refinery in the United States, was completely destroyed.

Investigators on the site quickly discovered the cause of the wreckage and the source of the explosion: sugar.

As raw sugar is refined and ground into ever smaller particles the potential explosion risk escalates as the total surface area prone to chemical reaction increases – as the surface area increases, the number of collisions between the molecules on the surface and the oxygen molecules in the air increases.

In the presence of a spark or flame, these molecular collisions become combustion reactions occuring at an increasingly rapid rate. Heat is released, triggering an increase in the volume of gases being formed, creating a shock wave. When the dust particles are suspended in air they can explode in the presence of an ignition source, such as a welding spark.

This process caused the catastrophic industrial plant explosion at the Imperial Sugar plant – a small spark or flame from plant machinery caused the explosions which instantly ignited and engulfed the plant. As the explosion rocked the plant and fire tore the plant to smithereens, accumulated sugar dust was tossed into the air further fuelling a series of explosions.

Further dust explosion hazards in the food processing industry include whole grains such as: maize, barley, wheat, oats, rye, soya beans, sorghum (milo). Flour, custard powder, instant coffee, sugar, dried milk, potato powder and soup powder also pose dust explosion risks in hazardous area locations.

Other industrial potential explosive dust atmospheres also include coal, metals, plastics and wood.

Rotronic hazardous area certified transmitters and instruments are for safe use in potentially explosive atmospheres, including both gases and dusts.

Rotronic HygroFlex5-EX

Rotronic HygroFlex5-EX temperature and humidity sensor is suitable for harsh but not hazardous area applications – due to being un-certified the sensor is therefore suitable for “safe” working areas. The stainless steel probe selected for the application from the Rotronic range available is rapidly interchangeable, no calibration adjustment required.

Rotronic HygroFlex5-EX – Hazardous Area Temperature Measurement ATEX Zone 1.

Rotronic Humidity & Temperature Sensors

atex certified for Hazardous Area Applications

• Interchangeable stainless steel probes certified for operation in Zone 0/20
• Standard and cable mount probes, screw-in probe for applications at pressure
• HygroFlex5-EX measurement transmitter certified for hazardous area Zone 1/21
• No intrinsically safe power supply required; galvanically separated
• Wall and duct versions of the measurement transmitter available
• 2-wire supply, 2-analogue outputs (inc.dew point, g/kg and moisture values)
• Sensor alarm – humidity and temperature can be set to fail high
• Robust aluminium transmitter housing; IP66 protection
• LC display option with trend indicators. Keypad for configuration
• Service interface (USB) for configuration using HW4 (outside explosion zone)
• Range of calibration accessories (for use outside the explosion zone)

Rotronic HygroFlex5-EX measurement device is the latest development in two-channel transmitters for the exact measurement of humidity and temperature in hazardous area industries with explosive atmospheres. Rotronic HygroFlex5-EX device conforms to the latest international standards.

Rotronic HF5-EX series consists of a robust aluminium transmitter with or without display. The attached probes are cast into a stainless steel tube and are certified for operation in hazardous area Zone 0/20 – the transmitter itself is certified for hazardous area Zone 1/21.

The intelligent design of the circuitry with electrical isolation permits the measuring system to be operated without an intrinsically safe power supply.

ROTRONIC HygroFlex5 (HF5)

pharmaceutical applications

Rotronic HF5 sensor is compatible with HygroClip2 probes with integrated AirChip3000 technology, which achieves an unparalleled degree of accuracy.

In combination with advances in sensor technology and integration, the Rotronic HygroFlex HF52, HF53, HF54, HF55 and HF56 transmitters combined with a HC2-S probe provide precision and functionality through accurate humidity and temperature measurement of <0.8% rh and <0.1K at 23°C.

Rotronic HF5 Features:

• Relative humidity and temperature measurement
• Dew point and other psychrometric calculations
• Interchangeable probe for easy maintenance
• Wide range of probes for every application
• Low voltage and mains versions
• Freely scalable analogue signals
• Various digital outputs available

Relative Humidity & The Pharmaceutical Industry

Pharmaceutical plant and process managers must implement control and measurement for relative humidity and “out-of-control” ambient temperatures. Humidity levels must be controlled and monitored using precision instruments where the pills are coated, stored and conditioned before packaging and despatch.

T&D UK are authorised distributors for Rotronic’s humidity measurement and temperature measurement instruments.

Rotronic manufacture devices, sensors and instruments for high precision measurement of Temperature, Humidity and Carbon Dioxide (CO2).

➡ See also: Rotronic HygroFlex5-EX – Hazardous Area ATEX Certified Transmitters & Calibration Rigs For Self-contained Reliance

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