supplying accurate output voltage < input voltage

It pushes air through a long hose to an airline respirator. So unlike a fan, it's pushing a small amount of air, 4-5 CFM typically, but high pressure is needed to push the air. Really, the people who are criticizing the motor design should send their ideas to Turbine Products. I'd be interested to hear what he has to say. Laura

It pushes a small airflow, like 4-6 CFM, through a long hose to a respirator. It needs to generate a lot of pressure to push the air, unlike a fan. Laura

It pushes air through a long hose to an airline respirator. So unlike a fan, it's pushing a small amount of air, 4-5 CFM typically, but high pressure is needed to push the air. Really, the people who are criticizing the motor design should send their ideas to Turbine Products. I'd be interested to hear what he has to say. Laura

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Do you have a link to any additional information, pictures, specs, etc.?

Greetings Laura, Can you supply any info on the motor itself? Not the current draw but the type of motor? Maybe a picture of the motor? I suspect it is a shaded pole motor. Also, you wrote about a rheostat controlling the motor speed. Is that all there is to control the motor speed? Just a variable resistor like a volume control in a radio? Thanks, Eric

He said it's a universal motor. It has brushes. It would be enough to control the input voltage, that's what I'm now trying to do by hand. I think if I were standing by the rheostat all the time, I could control the motor speed well enough. It's in a metal box, I don't know what's inside the box. What Jamie seemed to be saying is that there's some kind of feedback loop that might make the motor very voltage-sensitive, that he said would apply to a fan motor. This isn't a fan, it's an air turbine. In any case, this is what I have, and what I'd like to get running more evenly. It's not like there are a huge variety of airline respirators on the market. I'm not sure if the very expensive NIOSH-certified ones have more sophisticated motor control or not. I somewhat doubt it - I called one company and he said the innards were about the same for his NIOSH-certified version vs the home use version. These airline respirators are used by auto body workers or hobbyists, sandblasters, etc. Precise volume control might not be necessary for them. The voltage at an outlet does seem to vary more than the utility co. voltage, so I may have electrical problems that can be fixed and would give more even airflow. Laura

Here's what the guy who makes the respirator said, relevant to voltage sensitivity: "the motor speed change should be proportional to the voltage change, but that effect is amplified by the lowering of static pressure and the head loss in the air line, so the air flow reduction at free flow (at the air pump with no hose) would be reduced even more if measured at the end of the air hose."

The following sounds sarcastic, but the question is unavoidable...

WHY does the flow have to be so precisely regulated? Are you worried about bursting the lungs of the person on the respirator?

It would be much easier to have the turbine run at a constant speed and use a simple valve at the patient's end to bleed off excess flow. (Of course, if respirators were made that way, we wouldn't be discussing how to regulate the turbine speed.)

Because the motor is too noisy at high speed. Yes, excess flow passes through a valve to the outside.

Laura

You are the only person here who is their customer. You have a contractual relationship. You have a legitimate complaint with the product you gave them your hardearned money in exchange. Any queries a merely curious third party -- like the posters here -- might have can be safely ignored.

So it's OK if something designed to protect human life works like crap? I'm not sure how they figured that that was OK.

You said that the speed varied completely within a 20 VAC range --

Is this UL approved? Is there some safety standard it's supposed to comply with? Have you contacted NIOSH to tell them of your complaint?

Actually the other brands of airline respirators that I looked at don't even have a volume control. They just push air at a very high volume. Very loud. Laura

Okay. Then why is such tight regulation required?

Because it's noisy at high speed. Both inside and outside the mask.

e.

About how much would a UPS cost that regulates output voltage within

age.

ps Can anyone point me to such a UPS? thanks

If you remove the load from a series wound motor (universal), it'll increase in RPM's, greatly in many cases.

That type of motor is very sensitive to supply and exhaust flow..

essentially, you have a vacuum loader/cleaner motor.. The only way to properly regulate that is to measure the air mass flow and use that as the feed back. RPM's is going to vary to maintain flow.

In a series wound motor, like you have, it is almost a natural.

P.S. They make Brushless vacuum/blower motors that produce high volumes with integrated electronics for speed control of a simple 0..10 volts.

They just cost more... Are you getting the image now?

That is the idea of what I am talking about, however, that unit there is far to large for what you're talking about. You seem to think what you have is some high volume unit? It is actually very small compared to what I deal with. In your case, I can understand why. You don't need to be over inflated! ;)

Seeing that this is a medical device you have, I don't see you getting much help from those that cold make that unit more suitable for your needs, even though there are many that can do it for you. I think you understand what I am talking about there, it's to bad but that has what the world has turned to.

Personally, I can't believe they put in a universal motor, in the first place? You need to keep an eye on the brushes! They don't last like you think they should. It's called cheap, cheap!...

Jamie

I wonder whether a viable alternative is to control the air pressure rather than the voltage. Set the turbine output somewhat high and let an air pressure controller deliver the correct pressure to the mask.

Take a look at, e.g.,

I wouldn't worry too much about the motor's brushes wearing out too quickly. Lots of home appliances (vacuum cleaner, blender, hair dryer, coffee grinder) have brushes and last for years (albeit with intermittent duty).

She needs a Dyson Air multiplier :)

Jamie

ltage.

didn't see any specific responses, so

try search for UPS in the 200+VA range, to be certain it'll give no problems find something 400+ VA that is constantly running.

When you find something that you 'think' might work within budget; post a URL here and everyone will look at it and give excellent critiques.

Then you can buy it and be done with it.