How to test a Climateline heated hose

[mlmollenkamp]

Hose failures have come up off and on. I just went through a batch of about 10 hoses to check them electrically and thought I'd pass on my procedure. Note that I've never found a test procedure from Resmed, this is purely my invention.
Note that I was testing S10 hoses, but the S11 hoses should be the same.

You need a digital multimeter. It doesn't need to be expensive or fancy, although one with a temperature probe is useful and isn't a lot a lot more money.

First I tested using the temperature probe on my multimeter.
I have a felt cover on the hose and slipped the temperature probe between the felt and the hose, pushing it up from the machine end about a foot or so.
I put on the mask and ran the machine normally, breathing normally.
With my machine hose temperature set to 86 degrees I read 78 degrees after about 5 minutes, the starting temperature was the same as the room, 68 degrees.
The preheat feature on the machine does not seem to preheat the hose, only the humidifier.

Hose electrical testing:
First, Inspect the pins on the hose where it plugs into the machine. They should be solid gold color without any green or other discoloration. If there is any discoloration, discard the hose.

There are 3 pins on the connector that plugs into the machine.

With the connector facing up:
Test between the pin on the left and the center pin with the Ohm meter set to read a low resistance, usually 200 ohm range.
The resistance should be 9.7 ohms, although the exact resistance may depend on the calibration of your meter.
When I tested 10 tubes they were all exactly 9.7 on my meter.
A bad tube will probably read open (very high resistance), but its conceivable that they could short given the way the wires are wound on the hose. If its less than 9 or more than 10.5 on most meters I think it's bad, but I've never found a bad hose to know for sure.

Now set the meter to read a higher resistance (usually the 20K range) Test between the center pin and the right most pin. It should read about 12 k Ohms. The actual reading depends on temperature.
Reach inside the mask end of the tube and place your finger against the pin that sticks into the center of the connector. Hold it there for a minute or two, then read the resistance again. It should go down.
Mine went from 12.5 k at room temperature to 10.7 k with my finger on the sensor.
This is the thermistor that tells the machine what the air temperature is. If its way off the machine will think the temperature is higher or lower than it actually is.

The machine connector can become dirty. Especially if you touch the connector on the hose with dirty hands, or hands with cream on them etc. before connecting it.
You can clean it with contact cleaner that is available online. I like Deoxit D5 by Caig, but any cleaner that's safe for plastics should be OK.
If a known good hose isn't working try cleaning the connector on the machine.
First cover the air opening so no cleaner can get inside. A good way to do this is to connect an old non Climateline tube to cover the hole and outside of the pipe.
Use a small burst of spray directly into the connector. Now attach and detach a Climateline hose a few times to wipe the pins inside. Wipe off the pins on the hose with a lint free cloth after connecting it each time.
Cleanup any spray that might have gotten on the machine.

Finally, there is a document online, "airsense10-aircurve10_disinfection-guide_amer_eng.pdf" that gives the Resmed official instructions for cleaning machines and hoses for reuse in medical facilities.



I hope this is helpful.

[LSAT]

Why do you have 10 heated hoses and why do they need testing? I don't see the point.

[jimbud]

Why do you have 10 heated hoses and why do they need testing? I don't see the point.

Hose fetish and nothing better to do?

[Sleepzilla]

What exactly are you testing for, based on what specific measurements? (I don't mean to appear snarky, but you didn't say.)

The test procedure with the multimeter that you described merely verifies that the resistive heating element and temperature-sensing thermistor/thermocouple (also restive in nature) aren't broken or shorted etc. Beyond that, any resistance values measured with the multimeter are irrelevant without knowledge of their anticipated values and related function.

It doesn't verify that either the temperature sensor or heat output in the closed-loop control circuit are accurate and/or maintaining the hose temperature at setpoint. I.e. At the conclusion of your test you really have no idea if the components and control circuit are actually doing what they're supposed to be doing when they're supposed to be doing it.

The machine already does all of this automatically—and with much greater accuracy—on a continuous basis while operating. Unlike your relatively crude manual test procedure (no offense intended) the machine also knows what the measured values of both the resistive heating element and thermistor circuits should be in comparison to what they actually are. I.e. On a continuous basis during operation the machine is simultaneously aware of the temperature control loop's setpoint, process value, and corresponding variable output.

(The above is also how the machine automatically detects when a ClimateLine hose has been connected and/or disconnected.)

First I tested using the temperature probe on my multimeter.
I have a felt cover on the hose and slipped the temperature probe between the felt and the hose, pushing it up from the machine end about a foot or so.
I put on the mask and ran the machine normally, breathing normally.
With my machine hose temperature set to 86 degrees I read 78 degrees after about 5 minutes, the starting temperature was the same as the room, 68 degrees.

With respect, the above anecdotal observation is likely irrelevant because:
1) The control loop varies the hose heating element output as necessary to control air temperature delivered at the mask. It doesn't care about external hose temperature, especially midway down the hose under a felt cover, because
2) The hose temperature sensor measures only the delivered air temperature at the mask, and
3) The AirSense 10 clinical guide specifically notes that "the temperature and relative humidity settings displayed are not measured values."

The preheat feature on the machine does not seem to preheat the hose, only the humidifier.

When the Essentials Plus "Run Warmup" patient mode is enabled, the user can opt to preheat the humidifier tub (only) to a fixed temperature around 104°F (40°C) for about 30 minutes prior to starting therapy. During this water tub warmup period there's no air being blown through the hose, so it'd be pointless—and perhaps even harmful to the hose—to attempt to heat it at this point.

Note that I was testing S10 hoses, but the S11 hoses should be the same.

Nope. The S10 Climate Line hoses have 3 pins at the electrical connector, and the newer S11 hoses have 4 pins.

[Nocibur]

The definitive manual for troubleshooting ResMed Climateline tubing and similar devices is covered extensively in Electrical Testing And Maintenance Handbook, Vol. 11, AKA "The Electrician's Bible". Referring to Chapter 5, page 86, it is noted that evaluation of heated tubing can be classified into one of two categories:

"Worky"; and

"No Worky".

[Grumpy48]

The definitive manual for troubleshooting ResMed Climateline tubing and similar devices is covered extensively in Electrical Testing And Maintenance Handbook, Vol. 11, AKA "The Electrician's Bible". Referring to Chapter 5, page 86, it is noted that evaluation of heated tubing can be classified into one of two categories:

"Worky"; and

"No Worky".

When I worked in engineering we had another word for 'No Worky'....... 'FUBAR'. There are some slight variants on it's exact meaning, but they all suggest the same condition of a piece of equipment.

[mlmollenkamp]

1. I didn't say this was intended to diagnose or test the machine. Only to verify that the hose sensor and heater are still connected and not shorted. There aren't many failure modes for these things and if the resistances are correct it's almost certain the hose is OK. It's just a go/no go hose test, not a test of the entire system. I'm trying to help anyone who wants to verify that their hose isn't defective. Without measuring a few hoses it's difficult to know what the typical resistances are, I've not seen them published. It's better to rule out the hose before you decide the machine is defective.
People sometimes post that they don't think their hose heat is working, or that they've had a lot of hose failures. This is step one of a logical trouble shooting process.

2. I have so many hoses because I test them, clean them thoroughly then give them to people who's insurance doesn't cover them. I was once in that position and it would have been nice to have a spare hose, or a working one for that matter. Its a shame to throw away a perfectly good $40 hose twice a year. I used to pay for them and used them at least 2 or 3 years.

3. I like to change to a clean hose fairly regularly. Cleaning only one hose at a time is wasted effort, I can clean 3 or 4 just as quickly so I always have one to swap in.

I didn't intend start a fight, just hoping to help anyone who isn't sure if their hose is OK.

Feel free to do better.

[Nocibur]

Feel free to do better.

OK, let's take everything apart!!

A11 Service Manual:

https://www.manualslib.com/manual/34521 ... tml#manual

[zonker]

Feel free to do better.

LOVE it!

[Nocibur]

Feel free to do better.

LOVE it!

You love it that mollincramp's panties are in a bunch?

That's awful!!

[Nocibur]

The S10 Climate Line hoses have 3 pins at the electrical connector, and the newer S11 hoses have 4 pins.

I'd like to know how many users even own a DVM, much less how to use it.

That said, on A11 the outer 2 pins are the thermistor contacts, inner 2 the heater (they now have separate grounds).

[Conrad]

The S10 Climate Line hoses have 3 pins at the electrical connector, and the newer S11 hoses have 4 pins.

I'd like to know how many users even own a DVM, much less how to use it.

That said, on A11 the outer 2 pins are the thermistor contacts, inner 2 the heater (they now have separate grounds).

*Waves hand*

I have five of them, one bench model and four handhelds, all Flukes, and I know how to use them, mostly. lol

[Conrad]

The S10 Climate Line hoses have 3 pins at the electrical connector, and the newer S11 hoses have 4 pins.

I'd like to know how many users even own a DVM, much less how to use it.

That said, on A11 the outer 2 pins are the thermistor contacts, inner 2 the heater (they now have separate grounds).

*Waves hand*

I have five of them, one bench model and four handhelds, all Flukes, and I know how to use them, mostly. lol




To the OP

"There are 3 pins on the connector that plugs into the machine. With the connector facing up:"

In the description of your testing, is the opening of the heated tube facing you or facing away from you when you ID'ed the connectors? This makes a big difference, ya know?

[Sleepzilla]

I didn't intend start a fight, just hoping to help anyone who isn't sure if their hose is OK.

Feel free to do better.

LOL, who's fighting?

I was just pointing out the logical and technical reasons why your hose heater "test" isn't accurate, specific, or conclusive. Instead it simply just informs whether the heating element and temperature sensor are still intact. I.e. that they're not open circuits or shorted.

I was an electrical controls and instrumentation engineer for 30+ years, but in this case I don't need to do better, and neither do you.

The machine already automatically does everything your test does, only on a continuous basis whenever it is connected to power. As I wrote previously, that's why it also automatically detects the presence or absence of the ClimateLine hose and enables/disables the machine's heating circuit accordingly.

Below is the only test necessary for the ClimateLine hose:

[Grumpy48]

The S10 Climate Line hoses have 3 pins at the electrical connector, and the newer S11 hoses have 4 pins.

I'd like to know how many users even own a DVM, much less how to use it.

That said, on A11 the outer 2 pins are the thermistor contacts, inner 2 the heater (they now have separate grounds).

I think about 7 DVM's in different locations about the house and the workshops and 3 analog VOM's.

I confess that I also measured the AS10 heated hoses when I thought I was having a problem with one. My readings compare about the same as what mlmollenkamp measured. At low ohm measurements take into account the leads of the meter resistance and subtract that out of the hose measurement.