ISC posts test data

Is it possible that ISC is overly nervous about a clear contender for the Meg market that is rapidly gaining ground?

Or more likely annoyed by an obvious Meg knock-off.

It is quite interesting to note that ISC did not publish ANY test data until HH CCR made its way to market. Also quite interesting that ISC has focused on HH electronics, Golem Radial Scrubber and Golem BOV, all components of the HH CCR. Is it possible that ISC is overly nervous about a clear contender for the Meg market that is rapidly gaining ground?

Thanks for the detailed post Alex.

Did you or anybody else notice the inconsistency of the gases listed for each scrubber WOB test? On some they used 10/90, some air, some listed simply as 21 with no obvious method-why test a loop with 10/90 on a 50M dive? Why use 21(?) for a 90M dive? Shouldn't they use the same gas for each scrubber and each depth? Maybe it's just a mistake, I can't tell...

other units?? no idee as I did not test other units on WOB

I tested my unit on WOB, and it was impossible to repeat the result that was shown on their chart!

ISCs write up of the Hammerhead test is a bit misleading. Two tests were performed.

Electrostatic discharge.
This is a handling test that looks at a discharge of static electricity into the unit under test. It represents what would happen if someone walking across a nylon carpet in a dry environment were to pick up the unit, or perhaps touch a contact on the connector, resulting in static discharge.
The unit failed which is not good and shows a somewhat fragile design but has nothing to do with suseptability to radiated emissions which is what ISC are claiming.

Radiated Field test
This test checks the units suseptability to radiated electric fields, such as those from radio transmitters, HID lights etc. The Hammerhead apparently passed this test and is therefore has no problem with all the threats listed in ISCs paragraph starting 'Why is this important to you as a diver'


As an aside, the standard
Part 6-1: Generic standards — Immunity for residential, commercial and light-industrial environments
80 -1000Mhz at 3 Volt/meter doesn't seem appropriate for something that is expected to operate on a boats deck with Radar, VHF and HF radios in close proximity.


For anyone entering the wonderful world of EMC testing we have found that a set of knuckle bones and some fresh chicken entrails help in divining exactly what is wrong and how to fix it.


Simon

OK, I have gone through the ISC results in detail, comparing them with what we have for the same equipment and what CCR Ltd found on the same equipment. Our figures and CCR's are generally very close, for those configurations where we have both tested the same thing.

I have a number of comments that companies should take on board if they are to avoid a "my result is bigger than yours" type argument, when presenting rebreather test results. These are:

1. State your test conditions clearly. From the ISC figures it is clear they used fresh lime: the WOB tests should have been done with near exhausted lime because WOB risks from CO2 retention + O2 risks are most acute when the lime is nearing exhaustion. There is a big difference in the figures between fresh lime and exhausted lime in most scrubbers. This is important: with near expired lime our tests show it does not quite meet EN14143 WOB limits, but here with new lime, ISC are showing it does meet EN14143 WOB limits. Similarly, the attitude of the mannequin is not stated.

2. Print the calibration orifice Lissajou with your data. The ANSTI machine for the WOB tests appears to be out of calibration: there is a give away in the figures - the sinusoidal flow should not give sinusoidal pressure, or anywhere near it. There are some particular artifacts from sinusoidal flow, that are displaced. Please publish the reference Lissajou.

3. Keep the goal posts in one place when you are measuring competitor's equipment. The objective ISC stated in testing their own equipment was CE and EN14143 tests, but the figures used to compare the Golem BOV are not CE, not even NATO STANAG 1410, but some procurement document used by the US Navy. This is unfair on Golem. Yes, the Golem valve does have problems, but present it fairly please. Golem are not trying to sell this particular valve to the US Navy, AFAIK.

4. Inane suggestions such as those at the end of each of the ISC letters announcing results, detracts from their credibility and professionalism. The statements say that ISC's competitors should send ISC their equipment, so ISC can send it for testing to a third party (at an undisclosed cost which the competitor should cover), and the results shall be owned by ISC and the competitor. Why is this put in? It makes ISC look stupid, instead of doing something that should get undeserved credit.

Now to the results themselves:

a. The Extendair cartridge being tested clearly has a difference in test conditions compared to the other scrubbers. We suspect from the results, the flow direction is reversed. It is fair enough to do this, but if it was done, it should have been stated. We note the Golem test used reverse flow also. It makes both units look worse in comparison with others for WOB.

b. The statement about the ISC and Golem mushroom valves should have had a diagram of the test set up. We get higher figures for the ISC mouthpiece than is stated by ISC here. Is it just the mushroom valve being tested here, out of the mouthpiece, and if so, how is the gas getting back to the breathing machine?

c. The ESD discharge tests are reasonable, and the result is not unexpected. An ESD test is needed for dive kit, as well as RF emission and susceptibility, and 4KV is really a very low level discharge. Walk across a carpet or rip off a fleece jumper fast, and you can produce 25KV.

d. None of the test conditions seem to be those in EN14143. The 5 bar absolute figure should have been published, not the 6 bar (i.e. 4 bar relative to surface, not 5 bar relative to surface). The correct test depth is 40msw, as CCR Ltd show in their comparison, not 50msw. Both the HSE and ISC appear to have not read the spec carefully enough, and neglected to check with an accredited Notified Body, who could have put matters straight immediately.

e. CCR Ltd show the Meg as 2.76J/L WOB at 75l/min RMV in 40msw, with the 5.5lb axial canister. ISC show 2.5J/L at 50msw, which would be about 2.08J/L at 40msw. The difference is probably due to ISC using fresh scrubber material. A near expired scrubber should have been used on safety grounds for the reasons stated above.

f. Scrubber endurance, ISC 5.5lb axial scrubber CCR Ltd get 110 mins, ISC stopped the test too early, but get around double the CCR Ltd figure. This is very suspicious: the CCR Ltd figure is about right. The scrubber endurance test is very hard to do properly, and I suspect at the time this test was done the HSE were still learning how to do this: at the date they did these tests they did not have a lot of experience on their ANSTI machine. If this test result is to be accepted, a full disclosure of the exact test conditions should be made, including the breath by breath curve and the flow rates.

So bottom line, good step forward by ISC, but more professionalism is needed in presenting results. ISC should be able to address these gaps easily if they so choose to, and that would produce a set of results everyone could accept.

Alex

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