A number of years ago, our engineering team was asked to help a company that was doing full-system calibration checks once a week on over 125 sensors around their facility. The maintenance team was fighting with the safety team, since the safety team wanted to add many more sensors, but the maintenance team was struggling with keeping up with doing full system checks once a week. As we dug deeper and deeper to try to understand what was going on, we realized that the company’s corporate safety team had mandated the weekly checks because their chosen gas sensor technology would “fall asleep” seemingly at random and not provide any protection. There was even a person who would walk around and use her own nose to sniff for gas leaks of toxic gases – we were horrified! By using the sensor technology that they had chosen, they were putting their people at risk and spending a lot of extra time and money maintaining a system that they couldn’t trust.
And these exact situations are why Draeger designed their higher level diagnostic capabilities with the Draeger Sensor Diagnostic Dongle, a chipset that can be added to certain Draeger transmitters to activate three key diagnostic functions for most Draeger e-chem sensors:
1. Predictive Maintenance Life Indicator: Think of this as a “Battery-Level” of expected sensor life. As shown in the picture, the transmitter display features an icon that shows the sensor in one of three states – “extensive life left”, “mid-life”, and “replace soon”. The chipset regularly tests the sensor during normal operation, as well as after each calibration, to determine how exhausted a sensor is. Various factors are calculated to determine the sensor’s exhaustion, with the two main ones being temperature exposure (max and average) as well as gas exposure (max and average). A single horizontal bar indicates that sensor failure is likely to occur soon.
2. Vitality: This is a calibration-related numerical data point that provides useful information for a calibration technician to know how well the sensor is responding – what the sensitivity of the sensor is to gas. Calculated using past and current sensitivity readings to the gas, as well as knowing the overall life-time usage of the sensor, a number between 0 to 100 is displayed. A new sensor typically displays between 95 to 100 (indicating strong sensitivity), whereas a sensor that is fairly old and has very weak sensitivity could display very low numbers. As the sensor ages and is exposed to various gases, the sensitivity will typically continue to drop, although it can sometimes get higher. If a reading of 25 or lower is seen, it would indicate that the sensor probably needs to be replaced soon, or at least bumped / calibrated far more often than typical.
3. 10 Minute Health Check: Every 10 minutes, the sensor is electrical stimulated to observe whether it is functioning and healthy. If any error is detected, a sensor fault is given to warn that something is wrong, and the sensor needs to be checked or replaced.
Using Draeger’s unique sensor diagnostic chipset can definitely help to know when sensors should actually be replaced, as well as providing ample warning for imminent sensor failure!
One of our engineers was recently asked “What is unique about Draeger Sensors?” by a chemical company evaluating the technologies from various gas detection companies. The engineer talked for about 30 minutes about all of the special capabilities and design features of the various Draeger sensor, and the company who had asked the question was blown away – they immediately decided to switch to using Draeger for all of their future gas detection needs. After that discussion, we recognized that perhaps all of our readers would benefit from the discussion as well!
Draeger scientists are constantly challenging, testing, and improving their 30+ electrochemical sensor types that they manufacture at their facility in Germany. While there are dozens of unique technology features in
each sensor, we typically focus on six unique ones that set Draeger e-chem sensors (pictured) apart from most other sensors on the market:
Built-in Memory Chip: Draeger has had this feature around for 20 years, but it still sets the sensor apart. The memory chip stores calibration data, gas exposure data, temperature exposure data, and other useful maintenance data. The key one is the calibration data – Draeger’s e-chem sensors arrive from the factory pre-calibrated, so that once they are plugged into a Draeger transmitter with the ability to read the chip, the sensor can start being used once it warms up!
Diffusion Hole for Pressure / Humidity: Many years ago, an industrial gas supplier tested Draeger sensors against a variety of other sensors in environmental chambers that could vary temperature, pressure and humidity. The Draeger sensor performed so much better than all of the other sensors (i.e. almost no drift) that they thought something was wrong with it! However, Draeger has designed their e-chem sensor with both an internal temperature sensor as well as a diffusion hole in the side of the sensor that allows it to quickly adjust for any gradual temperature / humidity / pressure changes that might occur. This is especially valuable when the sensors are mounted outside, or around inside areas that could see significant swings due to outside doors opening and closing nearby.
Circular Chemical Reaction and Large Electrolyte Reservoir: Draeger e-chem sensors typically last a LONG time, and don’t need calibrated all that often (we recommend typically every 6 months). We’ve had oxygen sensors last 10 years in some environments! A lot of this is related to the internal chemistry that often has a replenishing reaction (the two reactions replenish the reactants), as well as a very large reservoir of electrolyte. Most sensors last at least 3 years, and the days of calibrating once a week or once a month are largely erased when using a Draeger sensor.
Cross-Sensitive Gas Testing: What’s one of the biggest challenges with utilizing a gas detection system? Workers not trusting the system because of false alarms. But how do you know which gases might drive a sensor to give an inaccurate reading? While not specifically a technology design feature, the data sheet for each Draeger sensor provides extensive information about various gases that Draeger has specifically tested against the sensor to determine whether there are any cross sensitive gases for users to be aware of which can yield positive or negative readings.
Gas-Specific Filters: What happens if you need to measure a gas, but there are definitely cross-sensitive gases that are also present that will definitely cause significant reading errors? In many cases, Draeger has designed gas-specific filters that replace the standard dust filter. These filters absorb the cross-sensitive gas for a period of time (until they are full), and allow a normal measurement to occur!
Self-Diagnostic Capability: Ever had a gas detection sensor “fall asleep” and not provide any warning whatsoever? That can be a major concern for a safety system, and can drive maintenance teams to do far more sensor calibrations / bump tests / replacements than necessary. Draeger has designed in two levels of sensor diagnostics – a standard level for every sensor that detects key problems, and a higher level from an added chip that we’ll address in our next blog (the Draeger Sensor Diagnostic Dongle). The standard level will look at things like calibration speed of response, calibration sensor gain level, sensor temperature, and a few other basics. But the higher level diagnostics are very powerful – read our next blog to learn more.
Combine all of these unique features together, and you’ll understand why company after company keeps switching to trust Draeger sensors for their safety needs!
Let’s start the conversation about how NSI and Automation Services can deliver peace of mind at your facility.
Newly Manufactured Pneumatics
Automation Service has purchased the equipment, manufacturing training and the rights to manufacture most of the Foxboro pneumatics, and is accepting orders currently for new pneumatics.
Remanufactured Control Valves
Remanufactured control valves can be produced with such precision and quality that they represent a viable alternative to new equipment. However, automatic control valves are not a “one size fits all.” Accurate sizing and proper specification are essential keys in providing the right assembly to meet the requirements of the application.
Once your order is placed, a product specific technician will build, test and calibrate your unit before sending it to our quality control department for final inspections. Once inspected and approved by one of our QC technicians, your unit is then shipped with a full 2-year service warranty.
Customers who are responsible for maintaining instrumentation and control valves within their facilities are allowed to retain the value of recycled assets for their specific department, as opposed to losing it to a general company-wide fund fed by scrapping or liquidation of these items. Make upgrades and complete projects, that seem unlikely due to budgetary restrictions, possible with the credits earned through our recycling program.
Product brand offerings include: Fisher, Foxboro, Rosemount, Micro Motion, Honeywell, Moore, Ametek, and Rotork.
Need more information? Contact one of our expert engineers!
Tank level measurements can be made in 50 different ways, which means our customers have a variety of options for their specific needs. In this application, the customer used a D/P cell “spud” type tri-clamp connection, which is easily removed for sanitary applications.
The large diaphragm of the seal converts the pressure from the fluid onto the pressure sensor in the transmitter housing. This pressure can be converted to level based on the density of the liquid.
The advantage of this method is that it is tried and tested for nearly every liquid level application and that you can get very close to the tank bottom to determine empty vessel conditions.
Because the customer is using an IGP10S transmitter w/ 11 different preprogrammed calibration curves, the transmitter is very accurate both at the high and low end of the tank.
Interested in this method? Contact one of our engineers here!