| HOW DO FID ANALYZERS WORK AND WHY USE THEM? |
| FID's are very selective to hydrocarbons only. FIDs show practically no interference from other components like CO, CO2, SO2, NOX, NH3 and many others. They respond very fast to very small changes of composition and concentration, which makes FID's the ideal tool to determine the presence of total hydrocarbon concentrations in a gaseous sample. In the detector burns a very small flame with hydrocarbon-free hydrogen and hydrocarbon free air (see image). Once a sample containing hydrocarbons is mixed with the fuel and is introduced into the flame, which burns between a high voltage electrode, and a collector electrode a complex ionization process is started. The electrostatic field between the two electrodes and the flame causes the charged ions to migrate to their respective electrodes. The migration of the charged ions generates a very small current, which is measured by the precision electrometer amplifier. This current is (nearly) proportional to the hydrocarbon concentration in the sample. |
| HOW DO THEY MEASURE HYDROCARBONS? |
| Our FID analyzers are equipped with an internal sample pump which continuously extracts an approx. amount of 2.5 liters of sample per minute from a gas stream. The sample pump generates a sample back pressure against a bypass capillary, which is precisely pressure controlled with a sample pressure regulator. |
| HOW AM I SURE MY RESULTS ARE CORRECT? |
|
The only way to make sure is the use of the highest quality fuel gas, the highest quality zero gas, the most accurate span gas and enough time to let an analyzer completely drift out in a low range before calibration. A good FID analyzer practically is nearly drift free. What you see drifting in a THC analyzer is hydrocarbons building up by condensing in the system, forming a hang up (also called a memory effect). Again: Clean FID analyzers are nearly drift free. Only a contaminated or defective FID analyzer (and sample train) drifts. The condensed hydrocarbons tend to accumulate on (in) sample-wetted materials like the sample lines, tubes, filters, valves and diaphragms. Once a hydrocarbon hang up has gotten old, it is difficult and time consuming to clean it off. In most cases, clean air, heat and your valuable time are the only tools. Calibrate your analyzer with zero gas and span gas as often as possible. When the circumstances allow, do it once (or twice) per day. The more often you calibrate, the quicker you see when a hang up starts to build up. When you get repeatable zero and span calibration results, your measuring results will also be correct and repeatable. Once you finished your measuring campaign or project, do not turn your analyzer off immediately! First, backpurge the sample filter for a few seconds. Then let your analyzer run clean by sampling low contaminated ambient air or zero gas for at least 60 minutes. Running your analyzer clean helps to remove residual hydrocarbons and other contaminants, which have been brought into the analyzer during sampling. These hydrocarbons would otherwise condense during the cool down period and contaminate the sample-wetted components. |
| HAS THE MANUFACTURER EVER CERTIFIED MY SYSTEM? |
| Technical products need preventative maintenance, so do your FID analyzers. For J.U.M. systems we strongly recommend to send us your analyzer about once every one to two years for detailed inspection, service and re-optimization. Maintenance for J.U.M. systems is done at our service location in Dickinson near Houston, TX. Only factory-trained technicians will service your equipment by strictly using OEM parts from the factory. We will be issuing a certificate of compliance for the unit that has been serviced and re-optimized to exactly meet the current factory specifications. The certificate is valid for 12 months. |
| MY SYSTEM SEEMS TO RUN BETTER AT A LOWER SAMPLE PRESSURE RATE? |
| Uhh, what's that?!?!? Any change of sample pressure (or other pressures) immediately change the characteristics of a FID-flame. The outcome simply is false measuring results and who wants this. Never change the sample pressure of a FID analyzer! When it seems to you that your analyzer works better at a lower sample pressure rate, something is wrong with the sample train or the analyzer, which requires immediate correction. |
