Don't know whether this is the right place to ask this but here goes....

One of our non-conformities was relating to the measurement and recording of airflow. Test method specifies "neglible" airflow. What does this mean? We have a detection limit of 0.02m/s on our equipment. How can I quantify neglible?

Any ideas?

Thanks. :confused:

Any ideas?Not really, but some reasoning, maybe? Neglible would mean "not enough to matter". Would 0.02m/s matter?

/Claes

What if our anemometer reads above zero (+/-0.02m/s)?
Does that mean that the airflow is no longer considered to be neglible?
Our readings tend to be in the region of 0.1 -0.2m/s is this to high to be negligible?

Help please I'm really confused!!!

Don't know whether this is the right place to ask this but here goes....

One of our non-conformities was relating to the measurement and recording of airflow. Test method specifies "neglible" airflow. What does this mean? We have a detection limit of 0.02m/s on our equipment. How can I quantify neglible?

You've got some 'splainin to do. What's the process and the exact requirement? What type of "equipment" are you talking about? What does "0.02m/s" mean? I can tell you what "negligible" means (insignificant; not worthy of consideration) but when it comes to standards, context is everything. "Negligible" is defined relative to what is significant, so you need to tell us more about what you're trying to accomplish.

Sorry. We are testing fire resistance of furniture coverings. We need to ensure that the airflow is negligible in the test chamber. We are measuring using a rotating vane anemometer in metres per second. It is my understanding that increased airflow can help 'feed' the flame.

Hope this clarifies things a bit.

Evidence of clearance of non-conformities have to be submitted by the end of the day - can you help???

What you describe seems quite a bit like some fire tests here in the U.S, under the ASTM standards.....I would have to look up the specific numbers but have seen most of them and done uncertainties on some.....

You are right about one thing.....airflow will help feed the flames.

The ASTM does not have a ststaement of "neglible" for the airflow, a specific range is specified. The standard that you use for the test may specify a range for acceptance.

If no range is specified, then let's discuss the anomometer.....if its best resolution is 0.02m/s and you are reading approximately 0.1 m/s, then the question becomes what is the full range of the instrument? If the full range is - say - 1.0 m/s, then the reading is way down at the low end and I would say that it qualifies as neglible.

Hope this helps.

Hershal

Sorry. We are testing fire resistance of furniture coverings. We need to ensure that the airflow is negligible in the test chamber. We are measuring using a rotating vane anemometer in metres per second. It is my understanding that increased airflow can help 'feed' the flame.

Hope this clarifies things a bit.

Evidence of clearance of non-conformities have to be submitted by the end of the day - can you help???


It sounds to me like you need to quantify the extent to which airflow in the chamber contributes to unreliable test results. Unless there is existing literature on the subject (or published standards) you might need to do controlled experimentation. You still haven't told us the criterion you're being measured against. If there were nonconformities, there must be some standard that you're expected to meet. The solution could be as simple as rewriting your own internal standard to state what the expectation is, how you measure it, and how you control it.

You are right about one thing.....airflow will help feed the flames.

If there's enough air flow, the flames will be extinguished.

If no range is specified, then let's discuss the anomometer.....if its best resolution is 0.02m/s and you are reading approximately 0.1 m/s, then the question becomes what is the full range of the instrument? If the full range is - say - 1.0 m/s, then the reading is way down at the low end and I would say that it qualifies as neglible.

I don't think I agree with this. If "negligible" is defined relative to the scale or resolution of the measuring device, it has no bearing on the affect of airflow on the testing. It doesn't matter whether the scale is 0-100m/s or 0-1 except possibly in terms of appropriate sensitivity. If 0.01 is negligible vis a vis the test requirements, it doesn't matter how far the anemometer will go.

If there's enough air flow, the flames will be extinguished.


That is true, though fire labs rarely have that happen without intent.....after all, the test typically involves flame (direct method) or heat from the flame (indirect method) on the item for some amount of time. At least, that has been the case in every fire test I have witnessed, with standards like ASTM E84 and E119 and others.....

The use of direct and indirect are mine, taken from the calibration methodology for current (I).

Hershal

We are testing fire resistance of furniture coverings. We need to ensure that the airflow is negligible in the test chamber.

It seems the interpretation of the auditor will determine what "negligible" means since he wrote you a non-conformance.

We do not test furniture coverings, but automotive interior components.
SAE J369 (Flammability of Polymeric Interior Materials) used for some Ford testing states:

The tests should be conducted with the metal cabinet in a draft-free fume hood. The face velocity of the fume hood shall not exceed 0.4 m/s.

While sitting in my office writing this, I feel a breeze from the heating/air conditioning ducts. If I can feel it, is it negligible or not? I would inform your auditor, after reviewing the past data for your chamber, that your readings, which you state are in the region of 0.1 -0.2m/s to be negligible.

If he does not agree, you have a :mad: on your hands. Good luck.

Aside from all the mumbo jumbo about measurement actinity of instruments, if a flow isn't specified then a measurement won't do. Since we know that it is a fire test and you want to make sure the flow doesn't affect the test, why not take a practical approach? Take a small candle (birthday?), light it, place it in the area where the direct flame impingement (or heat flux) is supposed to be for the actual test and make sure the flow doesnt blow out the candle. At least that demonstrates (and provides objective evidence) that the flow was negligible to the extent that it wouldn't blow out a candle. Now, if it is a test that uses a fllame source like that specified for the Flammable Fabrics Act, the size of the flame IS like a candle. Then you have other problems. However, if it is a flame from a Bunsen of Tirril burner, then you should be OK.

I am really grateful for all of the good advice I have been given. Due date for non-conformities is this Friday - will let you know how it goes!!!
:cfingers: