Sniffing out process problems

Photoionisation detectors have replaced other technology sensors to reduce false alarm rates for solvent leakage from pump seals.


ndianapolis-based Monument Chemical has switched solvent detection technologies at its speciality chemical production facilities in the USA and Europe in a bid to strengthen its regime of Good Manufacturing Practices (GMP) through improved monitoring effectiveness

across its processes. To achieve this, the company installed Falco fixed continuous photoionisation detectors (PIDs) from Ion Science to replace its existing Lower Explosive Level (LEL) sensors, which were prone to generating false alarms due to the phenomenon of steam quench around the LEL sensors Chosen for their humidity resistant design and accuracy, the high performance fixed PIDs are being used to monitor pump seals for potential leaks of different grades of solvents in the C6-C9 total aromatic compound (TAC) range. The Falco instrument provides reliable and accurate monitoring of potentially dangerous levels of combustible gas or solvent vapour, expressed in parts per million (ppm).

STABLE IN HARSH ENVIRONMENTS Several innovative design features of the Falco include the instrument’s ‘typhoon’ technology, which prevents condensation forming on the sensor and removes the risk of the system short circuiting – making it ideal for use in high humidity and harsh weather conditions. It has an externally located, intrinsically safe sensor which facilitates quick and easy servicing without the need for a hot work permit. Keyton Payne, Manager of Regulatory Affairs and Quality

at Monument Chemical explains, “When assessing the potential hazards involved in our day-to-day operations it became evident that Ion Science’s Falco fixed PID was ideal for our application. We were particularly impressed with the instrument’s patented humidity resistant fence electrode technology and ability to work continuously in condensing atmospheres. He went on to explain that the operations team were concerned that a more sensitive reading in parts per million (ppm) would lead to further false alarms. “However, since experiencing the unit’s performance, they have been very impressed by its stability,” he says.

CONTAMINATION PROTECTION The Falco PID incorporates Ion Science’s patented Fence Electrode Technology which virtually eliminates the effects of airborne humidity and protects from contamination. This advanced feature ensures reliability and accuracy in the field, while reducing drift issues and extending run time.

❱ ❱ The PID can be installed in chemical process installations for monitoring and process control, such as pump seal leak detection at Monument Chemical

Falco uses a diffusive sample technique resulting in fewer contamination issues compared to pumped systems, reducing lamp cleaning and servicing requirements. Pumped models are available for applications where a sample needs to be drawn to the unit.

DATA ACQUISITION AND CONTROL The Falco PIDs send data back to the Distributed Control System (DCS) every minute. The DCS software allows Monument Chemical to monitor trends and identify potential problem areas on a plant wide basis. The Falco’s flame and explosion proof enclosure is certified to EX d IIC T4 II and the external sensor to EX ib IIC T4 Gb II. A 4 – 20 mA analogue output enables Falco to be easily integrated into a DCS to give warning or control of high VOC levels in the working environment. Having two relay outputs means it can be connected remotely plus RS485 output with Modbus protocol included as standard allows the instrument to be connected to a network. Payne concludes: “The Ion Science team was always

available to answer questions and provide the help needed to set up and calibrate the PIDs in a very timely and concise manner. As a result, we would rate the service as excellent, easily a 9 out of 10.” n

DAQ, Sensors & Instrumentation Vol 1 No. 2 /// 9 ❱ ❱ The Falco Photoionisation

Detector provides alternative sensing technology for the detection of solvents

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