Re: Friction Loss in Oxygen Tubing?

February 17, 2007

In a message dated 2/17/2007 6:07:15 PM Central Standard Time,

texaslp@... writes:

In firefighting there is a calculable loss of pressure over a given distance

in a given diameter of hose at a given pressure. My question is: What is the

friction loss on oxygen tubing? Is anyone aware of a table or other

documented way to calculate this?

for a viscous fluid, including water, flow rate is proportional to the

delivered pressure and the square of the smallest diameter in the line, and

inversely proportional to the length of the tube/hose and the viscosity of the

fluid.

Considering the viscosity of a gas as compared to water, I suspect that

there is more of a problem with leaks in the connectors between the various

lengths of tubing.

ck

S. Krin DO FAAFP

February 17, 2007

I wondered this same question years ago and as a firefighter trained about

friction loss I got into a long debate over this same issue with a RT that I

worked with. As he explained and later showed me in one of his RT books,

there is only a negligible loss due to friction. It was explained to me that

as

a molecule of gas enters one end of the tubing, another comes out the other

end. The molecules of a gas are further apart than liquids and thus exert less

pressure against the sides of the tubing resulting in the negligible

friction loss.

I'm sorry I can't provide you with any source supporting this explanation at

this time.

" Scooter " Green FP-C

PHI / STAT Air 2

town, TX

February 17, 2007

In a message dated 2/17/2007 8:47:23 PM Central Standard Time,

Gadget95@... writes:

I wondered this same question years ago and as a firefighter trained about

friction loss I got into a long debate over this same issue with a RT that I

worked with. As he explained and later showed me in one of his RT books,

there is only a negligible loss due to friction. It was explained to me that

as

a molecule of gas enters one end of the tubing, another comes out the other

end. The molecules of a gas are further apart than liquids and thus exert

less

pressure against the sides of the tubing resulting in the negligible

friction loss.

If you want to get technical about it, the boundary layers for gas flow are

much thinner than with liquids, and it's in the boundary layers that most of

the friction occurs. This is due to the extremely low viscosity.

ck

S. Krin, DO FAAFP

February 17, 2007

In a message dated 2/17/2007 9:31:33 PM Central Standard Time,

rsmithhello@... writes:

Who cares what the loss is. If they are experiencing sob then give them the

o2. We are not scientists. Is are treatment going to be any different if we

know the loss that is occurred with long tubing I think not.

and that, Sir, is the difference between a trained technician and an

educated professional!

The technician will only care that they need to provide a shorter tube or a

higher flow rate to compensate...the provider will understand how and why the

problem is occurring and be able to teach the patient and the patient's

family how to avoid the problem in the future.

I believe that we have been talking about the need for increasing the

professionalism of EMS?

ck

S. Krin, DO FAAFP

February 17, 2007

In a message dated 2/17/2007 9:44:34 PM Central Standard Time,

texaslp@... writes:

I do explain to the patient and family that the excess tubing is

probably causing a reduced " end-user " flow rate and that they should

consider not having a mile of tubing from one end of the house to the

neighbors and back. I also encourage them to speak to their doctor

and/or oxygen supplier about a remedy for this.

ck: Excellent...so you are acting as an educated provider, and not just a

trained technician.

According to the table I referenced; there is a loss of 8.66 PSI @ 20

CFM / 100' of smooth PVC with a diameter of Â½ " . Again, I am too tired

to attempt a conversion (or Krin's inversely proportional of the

inverse of the square of the diameterâ€¦â€¦â€¦â€¦or whatever it was) tonight.

I think he has probably answered this question best though in that

the connections are the fallacy of these multiple extension sets.

Chuckle...considering we are talking about probably 15 psi delivered, 1/8

inch effective diameter, and a flow on the order of 4 lpm...and at 28 liters per

cubic foot....I suspect that the effective loss is different.

ck

February 17, 2007

,

I too wonder this..but one thing we stopped doing, and I would encourage you to

be cautious about...is turning up the O2 on the concentrator and leaving it

turned up. I know with my dad who had COPD for 10+ years, his physician

controlled and really warned against using more oxygen than the doctor told him

to use.

We tell our crews to put the patient on the oxygen we bring in at a rate and

device appropriate for the dyspnea the patient is having...and transport them

for treatment/evaluation at the ED...then when they come home the concentrator

is set where it is supposed to be set and we don't accidentally encourage the

patient becoming more dependent on supplemental oxygen than the natural course

of the disease is going to make them.

Any one know the answer to the question if oxygen level is lost in longer

lengths of tubing? Would be interested in the science...I can't remember my Gas

Laws but just thinking it through I'm not convinced the loss would be that

great...any lurking physicists on here?

Dudley

Friction Loss in Oxygen Tubing?

We have all been on difficulty breathing calls where there is a patient on

oxygen by nasal cannula via an oxygen concentrator in the home. The delivery

rate is generally 2 LPM and quite predictably there is 25 (yeah right, more like

100) or more feet of extension tubing between the concentrator and the patient.

My initial â€œtreatmentâ€ is to either remove the miles of extension tubing or

to simply turn the delivery rate way up. This usually â€œfixesâ€ the problem.

Then I attempt to educate the patient and / or the family about the loss of flow

over that length of tubing.

In firefighting there is a calculable loss of pressure over a given distance in

a given diameter of hose at a given pressure. My question is: What is the

friction loss on oxygen tubing? Is anyone aware of a table or other documented

way to calculate this?

Here are a couple of internet resources I found on the subject. The second is

listed in the first but deals with cubic feet and much larger pipe not LPM or

oxygen tubing. I am a little tired, so I didn't even attempt to make conversions

(I assume they could be done with the right mathematical genius running the

show) with the tables' information (maybe one of you rocket scientists can).

http://forums.firehouse.com/showthread.php?t=66431

http://www.aquatext.com/tables/frict-air.htm

In asylum,

E. Tate, LP

---------------------------------

Any questions? Get answers on any topic at Yahoo! Answers. Try it now.

February 17, 2007

Who cares what the loss is. If they are experiencing sob then give them the o2.

We are not scientists. Is are treatment going to be any different if we know

the loss that is occurred with long tubing I think not.

" E. Tate " wrote: We have all been on

difficulty breathing calls where there is a patient on oxygen by nasal cannula

via an oxygen concentrator in the home. The delivery rate is generally 2 LPM and

quite predictably there is 25 (yeah right, more like 100) or more feet of

extension tubing between the concentrator and the patient. My initial

“treatment” is to either remove the miles of extension tubing or to simply turn

the delivery rate way up. This usually “fixes” the problem. Then I attempt to

educate the patient and / or the family about the loss of flow over that length

of tubing.

In firefighting there is a calculable loss of pressure over a given distance in

a given diameter of hose at a given pressure. My question is: What is the

friction loss on oxygen tubing? Is anyone aware of a table or other documented

way to calculate this?

Here are a couple of internet resources I found on the subject. The second is

listed in the first but deals with cubic feet and much larger pipe not LPM or

oxygen tubing. I am a little tired, so I didn't even attempt to make conversions

(I assume they could be done with the right mathematical genius running the

show) with the tables' information (maybe one of you rocket scientists can).

http://forums.firehouse.com/showthread.php?t=66431

http://www.aquatext.com/tables/frict-air.htm

In asylum,

E. Tate, LP

---------------------------------

Any questions? Get answers on any topic at Yahoo! Answers. Try it now.

February 17, 2007

Dudley,

Just for clarification. I am a FD First responder. What I meant is

that we commonly turn up the concentration, remove excess tubing, or

place the patient on our O's to remedy their dyspnea. Generally, I am

in contact with the patient ahead of the rookie or in my case my

Captain (and who says EMS " rank " doesn't have its privileges?)

bringing in our O's. I have found that simply turning the

concentrator up to 4 - 6 LPM has them all better before my guys can

even produce the O's and assemble the delivery device (generally a

non-rebreather for us). Once a box arrives they will transport to the

appropriate facility as necessary and we go back into service. We

don't just turn it up, explain to them to do the same, and leave.

Sorry for the confusion if this was the case.

I do explain to the patient and family that the excess tubing is

probably causing a reduced " end-user " flow rate and that they should

consider not having a mile of tubing from one end of the house to the

neighbors and back. I also encourage them to speak to their doctor

and/or oxygen supplier about a remedy for this.

According to the table I referenced; there is a loss of 8.66 PSI @ 20

CFM / 100' of smooth PVC with a diameter of ½ " . Again, I am too tired

to attempt a conversion (or Krin's inversely proportional of the

inverse of the square of the diameter …… or whatever it was) tonight.

I think he has probably answered this question best though in that

the connections are the fallacy of these multiple extension sets.

I have queried a couple of Respiratory Therapy instructors that I know

to see what their " science " says about the matter. When I get a

reply, I will post to the list.

In asylum (not in the asylum),

Tater

>

> ,

>

> I too wonder this..but one thing we stopped doing, and I would

encourage you to be cautious about...is turning up the O2 on the

concentrator and leaving it turned up. I know with my dad who had

COPD for 10+ years, his physician controlled and really warned against

using more oxygen than the doctor told him to use.

>

> We tell our crews to put the patient on the oxygen we bring in at a

rate and device appropriate for the dyspnea the patient is

having...and transport them for treatment/evaluation at the ED...then

when they come home the concentrator is set where it is supposed to be

set and we don't accidentally encourage the patient becoming more

dependent on supplemental oxygen than the natural course of the

disease is going to make them.

> Any one know the answer to the question if oxygen level is lost in

longer lengths of tubing? Would be interested in the science...I

can't remember my Gas Laws but just thinking it through I'm not

convinced the loss would be that great...any lurking physicists on here?

>

> Dudley

>

> Friction Loss in Oxygen Tubing?

>

> We have all been on difficulty breathing calls where there is a

patient on oxygen by nasal cannula via an oxygen concentrator in the

home. The delivery rate is generally 2 LPM and quite predictably there

is 25 (yeah right, more like 100) or more feet of extension tubing

between the concentrator and the patient. My initial â€œtreatmentâ€

is to either remove the miles of extension tubing or to simply turn

the delivery rate way up. This usually â€œfixesâ€ the problem. Then I

attempt to educate the patient and / or the family about the loss of

flow over that length of tubing.

>

> In firefighting there is a calculable loss of pressure over a given

distance in a given diameter of hose at a given pressure. My question

is: What is the friction loss on oxygen tubing? Is anyone aware of a

table or other documented way to calculate this?

>

> Here are a couple of internet resources I found on the subject. The

second is listed in the first but deals with cubic feet and much

larger pipe not LPM or oxygen tubing. I am a little tired, so I didn't

even attempt to make conversions (I assume they could be done with the

right mathematical genius running the show) with the tables'

information (maybe one of you rocket scientists can).

>

> http://forums.firehouse.com/showthread.php?t=66431

> http://www.aquatext.com/tables/frict-air.htm

> In asylum,

> E. Tate, LP

>

> ---------------------------------

> Any questions? Get answers on any topic at Yahoo! Answers. Try it now.

>

February 17, 2007

Rob,

You are kidding..... right?????

Tater

We have all been on

difficulty breathing calls where there is a patient on oxygen by nasal

cannula via an oxygen concentrator in the home. The delivery rate is

generally 2 LPM and quite predictably there is 25 (yeah right, more

like 100) or more feet of extension tubing between the concentrator

and the patient. My initial " treatment " is to either remove the miles

of extension tubing or to simply turn the delivery rate way up. This

usually " fixes " the problem. Then I attempt to educate the patient and

/ or the family about the loss of flow over that length of tubing.

>