- Detection Limits – How are they calculated and how consistent (stable) are they?
- Accuracy – Has the instrument been compared to standard filter based analysis?
- Operation – How difficult is the instrument to operate?
- How often does the site have to be visited and by staff with what level of training?
- What consumables are used and how often do they have to be changed?
- How much power does it use?
- Are there any precautions required for X-ray radiation?
- How does the instrument handle moisture and hot or very cold weather?
- What is the cost of the instrument and what is necessary for installation?
1. Detection Limits – How are they calculated and how consistent (stable) are they?
Our instruments are calibrated using thin film standards as prescribed in the EPA Compendium Method IO-3.3 for the Determination of Inorganic Compounds in Ambient Air, EPA/625/R-96/010a, Table 2, page 3.3-16. The instruments are extremely stable, normally only requiring recalibration after an X-ray tube has been replaced. We have rarely observed a calibration drift more than +/- 5% within the life time of an X-ray tube. When it has occurred, the calibration was typically only out of range for one or two metals. It is only those metals that required recalibration, which reduces the downtime and labor for recalibration.
2. Accuracy – Has the instrument been compared to standard filter based analysis?
The Xact® 625 (ambient) has been compared by independent laboratories around the world vs. SRM. We do perform a linearity test by following the M301 dynamic spiking protocol. We quantitatively spike ambient air for the purpose of determining accuracy and precision of our calibrations. The Xact® 640 (stack CEMS) has earned EPA acceptance for an alternative method of monitoring Hg, Pb, Cr, Cd and As from a hazardous waste incinerator by method 301. This method includes procedures for determining and documenting the quality, i.e., systematic error (bias) and random error (precision), of the measured concentrations from an effected source. If you would like, I can send a paper we published regarding the data produced during this M301.
3. Operation – How difficult is the instrument to operate?
Our instruments do not have a large number of set-up options, so this simplifies operation. If you were to remotely poll the data you will only need to visit the instrument for tape change, maintenance and infrequent repair. Once installed the Xact® 625i monthly maintenance tasks are a flow calibration check, XRF check and QA blank check. If the instrument is utilizing an hourly sample protocol then the tape change and the monthly checks coincide and collectively consume 2-3 hours.
4. How often does the site have to be visited and by staff with what level of training?
The training course given to all clients allows any competent technician to perform the basic tasks (tape change and monthly maintenance) required to operate any of our instruments. Xact installation, calibration and repair are a separate training session to skilled technicians with at least two years of experience.
5. What consumables are used and how often do they have to be changed?
This depends on what instrument the client is operating. Our Xact® 640 (stack multi-metal CEMS) has more consumables than the Xact® 625i (ambient). The Xact® 625i consumes only filter tape. Depending on your sample period length, tape changes will occur between every six days to 2 months.
6. How much power does it use?
We require 20 amps of 120 VAC/60 Hz conditioned power to operating our CEMS, and 10 amps of 120 VAC/ 60 Hz for the ambient model.
7. Are there any precautions required for X-ray radiation?
It is most likely that your state health board will have maximum x-ray leakage requirements that cannot be exceeded. We can assist you with the approval process if needed. All our instruments are designed with redundant safety features to assure safe operation and meet requirements. We test all the instruments we build for x-ray leakage prior to shipment.
8. How does the instrument handle moisture and hot or very cold weather?
The XRF package requires operating conditions identical to an office building. Our instruments are usually housed in a temperature controlled shelter with filtered air. A standalone instrument platform utilizing NEMA 4 or 4X instrument enclosure is also available if mobility is required.
9. What is the cost of the instrument and what is necessary for installation?
Client applications vary and site specific information is required to correctly suggest the proper instrument to answer their monitoring needs. Please schedule a time with us to discuss your specific monitoring questions, so that we may configure the proper instrument for your application?