Pressure generator

Projects General Guidance
1

Hi guys,

First of all sorry for my English.

I'm completly new to arduino.

I would like to build next:
Pressure generator which would be able to pump pressure to 50, 100, 150, 200 and 250 mmHg and then go back to 200, 150, 100, 50 and 0 mmHg.
It should pomp to 50 mmHg and wait until I give it command to go to 100 mmHg and so on..

I have some parts from blood pressure devices:
-pumps
-elctromehanical release valves,
-pressure sensors

So, which arduino is best for this project, how to program it, etc.

If I forget anything, please tell me

Thank's for your help.

Regards,

2

Hi, welcome to the forum.

The Arduino Uno is the easiest board to start with for any project.
It is a 5V board, so it would be nice of your pressure sensors would work at 5V.

Can you tell more (everything) about the valves, the pump, the sensors ?

A 6V or 12V valve or pump can be controlled with a mosfet or a transistor.
It is an analog pressure sensor ?

3

Hi Peter_n,

Thanks for quick reply.

I have 6V blood pressure pump, 3V air release valve. I have also sensors from blood pressure monitor(not sure on what voltage do they work). The monitor works on 4x1.5V AA batteries.

4

You'll need a transistor or MOSFET to drive the pump and valve, and you'll need a voltage regulator for the 3V valve. (Or maybe you can tap-into the batteries and just use 2 batteries for 3V.)

You'll also need a pressure sensor, and possibly an op-amp or something to get a sensor output somewhere in the 0-1V or 0-5V range.

Since you are apparently "hacking" an existing blood pressure monitor, you may have all of these things if you can figure-out how to utilize them.

5

The pressure sensors might be analog, and they might need an opamp to amplify the signal.
That is the cheapest way to build an blood pressure meter. Without opamp, you might not be able to read them. Do you at least know which pins are the power and ground pins of the pressure sensors ?

6

Hi,

I don't have sensor with me at the moment (it's in my workshop), but it's something similar to this

SX100DN datasheet - Specifications: Operating Pressure: 100 PSI ; Output:.

I would like to build this generator to calibrate blood pressure monitors. So I have reference pressure meter connected with testing device(blood pressure monitor) and t-piece with manual ball hand pump.

I would like to establish automatic sequence (with pump and arduino) not with hand ball pump.

7

do you have all you need for design of the hardware, pump, valves, etc ?

seems that generating the pressure is not that hard, generating highly accurate pressure would be a bit more difficult.

I had designed a unit a couple decades ago, for use in calibraing pressure transducers.
you put the unit, zero, go to one level, allow it to stabilze, hand write the error, repeat.
you multiple level process brings back memories.

8

Yes Dave exactly that. I would like to eliminate hand pumping an stabilizing at every point.

I have everything in my workshop (pump, air release solenoid valve, sensors) from old devices.

I'm looking for help with arduino boards (which to chose) and also programming.

9

It will be so much easier if you buy a temperature compensated pressure sensor with (for example) 0..5V output.
If you don't know the type, it might not be linear and not temperature compensated and with a small analog bridge output signal.

Perhaps the pump will work at 5V ? Can it build enough pressure at 5V ?
How to control the valves, depends on the current it needs.

Will the pressure sensor be in the same level as the blood pressure meter under test ? Because valves leak.

10

the UNO is the defacto standard to start with. the number 1 reason is that the shields are made to plug in and then work without having to make circuits.

in your case, you will need some cirucits, so the NANO or Micoro, the ones with the on-board USB chips make great sense.

first, if can make a compressor that can generate the pressures you needs and you can turn it on and off with a switch, you can replace the switch with a relay and some control of the Arduino.

if you can install a pressure gauge, and then feed that back to the Arduino, the arduino can use that as the reference point to create the on/off signal for the pump and valves.

add a selector switch for the level you want, feed that to the Arduino and presto, you have a complete system.

couple relay boards from e-bay are cheap.
a NANO or MICro from e-bay, easy and low cost

250 mmHg or 3/4/in W.C or 0.35 PSI is very small for many devices.
do you have a sensor that has a full scale to around 250-300 mmHg ?
there are many manufactures that make these low pressure sensors. much better to get one that is in this range than to get one for a much higher range and then only use a fraction of the range.

Peristaltic pump can generate these pressures, but not high flow.
an air brush generator can as well
I think a decent fish tank pump can also generate a couple PSI so they should be able to do that a well.

my experience is that a pump will deliver a very noisy signal. every stroke is similar to a small fire cracker going off inside of the vessel.

I used a pressure regulator, a capacity tank, then a second pressure regulator, in an effort to remove most of the fluctuation caused by the pump.