[Stoves] Aprovecho's ISO certificates

Wed Oct 18 13:41:31 CDT 2017

Dear Nikhil and Xavier

>Another thing -  when you bring up LEMS hood, are you saying that Aprovecho uses LEMS and that Berkeley (UC? BAMG?) analyzed the equipment to conclude that it could not rate stoves beyond Tier 3.5 for some emissions? Or efficiency?

Firs we have to separate the test method, the analysis that is made using the test results, and the test apparatus. These are distinct in the normal world, and confabulated in things like the WBT document. This has led to a confusion in the minds of many about what constitutes the test protocol and the test sequence. The latter is what you do with the stove while implementing the test method.

So…let’s discuss this on these separate bases.

The Berkeley review was by a group independent of the BAMGroup and independent of Aprovecho. It was a straight forward technical assessment which if I recall (and it is ‘normal’) was on the basis of the limit of detection being 1/3 of the available resolution. There is an indirect reference to this in the IWA where it discusses the result required to declare a stove to be on a tier. They asserted that the LEMS/PEMS system was in the limit at ‘tier 3.5’ which of course doesn’t exist, but if it did…

Next, nothing prevents Aprovecho from upgrading its equipment in terms of accuracy and precision. I understand that they did make changes, announced here, in January 2016, correct? As far as I have read, they do not make claims for their limits of detection and limits of quantification (LOD/LOQ).

All this has nothing to do with the problems of the WBT which is a test procedure and analytical method. As discussed here ad nauseum, the WBT analysis creates additional uncertainty by inflating experimental errors.

>This may be significant since to my recollection, EPA did not bring in PM2.5 regulations for regulated entities until 1997. From what I remember of EPA approved laboratories for PM2.5 emissions for residential wood heaters - i.e., heating stoves - Aprovecho wasn't one of them.

To my knowledge they have never made that claim. They have often offered and been paid for testing services. Similarly, Berkeley Air offers testing but I do not know what the equipment is. If they claim a stove is ‘tier 4’ according to the IWA, it cannot be with a LEMS prior to January 2016.

>Now, Aprovecho may not want to test for wood heating stoves in the US and nonetheless want to test and certify wood cookstoves for the developing world.

They do offer that service.

>What I am wondering is whether by setting Tier 4 for PM2.5 emissions as low as EPA did in IWA 2011:12,  and lower than those for US NSPS for residential wood heaters, EPA was setting up the ISO exercise in such a way that no wood cookstove would be tested above 3.5 Tier.

No, that is a misunderstanding. The Tier 4 target for the IWA was supposedly based on work by the WHO, as explained in the document, but that work was entirely ignored by the latest exercise. In both cases the claim was made that the emissions were related to exposure and health. As discussed here, again ad nauseum, making such claims is challengeable on several grounds, not the least of which is that the single box model advanced by Berkeley to make the calculation is nearly irrelevant for predicting exposure.

It has nothing to do with the Tier 3.5, which is entirely about making claims using particular apparatus.

>To your knowledge, is this a protocol issue or an equipment issue, or both?

Separately, any set of equipment can be rated using a protocol to see what the LOD and LOQ numbers are. The IWA sensibly sets a ‘quality’ requirement for results. From that, equipment can be assembled with an eye on the protocol so the result is within specification. As everyone knows, that is not what people are doing, They are specifying equipment first, using it, and then looking to see if it meets the spec (or not). The 19867-1 document was prepared in the same manner as there was no one member capable (willing?) to do the necessary investigation.

The Masonry Heaters Association investigated the EPA method and equipment and found that it was not nearly as good as the much cheaper Condar system when it comes to rating the performance of very clean fireplaces. The EPA’s system was designed for much larger and dirtier systems than small cooking stoves so should not be a surprise that it struggles with them. I have never seen a tier-related rating of the EPA system.

>Who certifies LEMS equipment and for what purpose?

It does not come with a certificate, not even the independent review conducted by Berkeley. It is similar in operating method to the EPA total capture dilution system, as is the math underlying it. The instructions say that it should be returned annually to Aprovecho for calibration. A lab using the system will probably want to perform their own calibrations and linearization much more frequently than that. The SEET and BEST/CAU lab calibrates gas measurements daily. PM is zero-calibrated daily. Scales should be calibrated annually, and thermocouples twice in that time. Harold Annegarn says that a certifying lab should spend about 20% of its time calibrating equipment.

There is a fairly straightforward method of testing a set of apparatus: have different labs test a stove and compare results. To get an ISO 17025 certificate, that is the standard procedure. You replicate someone’s result. The definition of ‘replicate’ is contained in some ISO documentation.

Regards
Crispin

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