By Rick Andrew
There are many different types of laboratories—medical laboratories, microbiological laboratories, physical-testing laboratories, pharmaceutical laboratories… the list goes on and on. And each of these has its own complexities. Today’s demands for highly specific and accurate data lead to the use of very sophisticated instruments operated by highly trained and often highly educated technicians, using complex information systems to accumulate, analyze, manipulate and report data.
So what does it take to put together a state-of-the-art POU and POE testing laboratory? The answer may not surprise you: it takes a combination of very sophisticated instruments, highly trained technicians and complex information systems. But this is just a high-level view. There are many pieces that fit together very precisely to form this testing laboratory puzzle.
Figure 1 describes 16 puzzle pieces, each of which is critical for building a high-quality POU/POE testing laboratory. These puzzle pieces include:
Accurate data reporting
Because of the volumes of data involved in POU/POE testing (see Data handling), accurate reporting can become challenging. And, results can be dramatically affected if numbers are transposed or data is somehow erroneously reported.
Accurate flow control
The contaminant-reduction performance of POU/POE systems can be very dependent on flowrates. Useful test results require accurate flow control by the laboratory.
Accurate flow measurement
Accurate flow control is impossible without accurate flow measurement.
Accurate particle counting
Nominal particulate reduction testing under NSF/ ANSI 42 requires counting of particles in the range of 0.5 to 120 microns. Sophisticated laser-particle counting instruments, operated by qualified and trained technicians, are necessary to achieve accurate counts or particles for this testing.
Accurate pressure control
Testing at the correct pressure is critical to achieving correct results for structural integrity testing, for contaminant reduction testing under NSF/ANSI 53, for measurements of flowrates of UV systems with flow controllers under NSF/ANSI 55 and in may other instances of testing POU/POE equipment.
Accurate pressure measurement
As with flow control and flow measurement, accurate pressure control requires accurate pressure measurement.
Huge amounts of data are generated when testing POU/POE equipment. The typical chemical reduction test under NSF/ANSI 53 requires analysis of influent and effluent samples at six different sample points, resulting in 18 data points specifically for the contaminant being tested. These tests also require constant measurement of temperature, pH, TDS, pressure and other test characteristics. This is just one example of the massive data requirements associated with POU/ POE testing—there are many others.
Analysis of trace level organic contaminants by GC/MS is necessary for organic contaminant reduction testing under NSF/ ANSI 53 and is critical for analysis of potential organic contaminants when conducting extraction testing. This includes capability for analysis of both volatile and semi-volatile contaminants, using sample preparation and introduction methods, such as purge and trap as well as solvent extraction, possibly derivitization and direct injection.
Analysis of trace-level metals is necessary for heavy-metal contaminant reduction testing under NSF/ANSI 53, 58 and 61 and, similar to GC/MS, is critical for analysis of potential heavy-metal contaminants when conducting extraction testing.
Certain contaminants are best analyzed by ion chromatography, including nitrate, nitrite, chloride, sulfate and others. Advanced ion chromatography techniques are required for analysis of perchlorate at trace concentrations and other ionic analyses that could be relevant to POU/POE testing.
Several types of tests for POU/POE products require the ability to culture various microbes and enumerate them. These tests include bacteriostatic effects under NSF/ANSI 42, live cyst reduction under NSF/ANSI 53, UV performance testing Class A and Class B under NSF/ANSI 55 and microbiological reduction under NSF/ANSI 62.
Many of the contaminant reduction tests under the NSF/ ANSI DWTU Standards require testing 16 hours per day, so laboratories must be staffed and organized to run two shifts.
RO/DI water is required as a starting point for many of the tests under the NSF/ANSI DWTU Standards. Laboratories must have an RO/DI system capable of delivering water with one-μS/ cm conductivity in volumes sufficient for their needs.
Most tests under the NSF/ANSI DWTU Standards require at least two test units. These units range in size from small, faucetmounted models to relatively large POE systems. Laboratories must be prepared to receive, handle, store and ultimately return ship or dispose of all sizes of test products.
Stable influent challenges
Most contaminant reduction tests conducted on POU products, and especially on POE products, take more than one day to complete. It is very important for achieving accurate results to have influent challenges that are as stable as possible. In some cases, fresh batches of contaminant challenge water must be prepared and checked daily for the duration of the test. In other cases, the test water must be stable for the duration of use. Well-qualified, trained and disciplined technicians are a key to stable influent challenges.
POU and POE product testing is best handled through the use of purpose-built test stands. These stands typically include connections capable of handling various types of installations, ranges of flowrates and sizes of units. They are designed to allow the accurate flow control and measurement, pressure control and measurement, and stable influent challenges described above. Test stands also usually incorporate some automated and some manual data entry, manipulation and storage within a database.
The puzzle is now complete
Much like building a 1,000-piece jigsaw puzzle with pieces that are all similar in color (ever tried this? I don’t recommend it!), assembling a state-of-the-art POU/POE testing laboratory is no small feat. It is a combination of expensive and appropriate analytical equipment, properly qualified and trained staff and custom-built test stands capable of accurate delivery and measurement of water. It is built on a foundation of precision and accuracy, of quality and detail and of sound data. And when it is all working correctly, it is a source of impartial and invaluable data about the design, construction and capability of POU/POE equipment for treating and providing safe, clean drinking water for our families. Now that’s a puzzle I can appreciate!
About the author
Rick Andrew is the General Manager of NSF’s Drinking Water Treatment Units (POU/POE), ERS (Protocols) and Biosafety Cabinetry Programs. He has previously served as the Operations Manager and, prior to that, Technical Manager for the program. Andrew has a Bachelor’s Degree in chemistry and an MBA from the University of Michigan. He can be reached at (800) NSF-MARK or email [email protected].