Axial Swash Plate Feed Pump

[The Ignoble Troll]

Let me get back to you.

I have some ideas.

Actually... I am getting silly. I was going to go Into figuring out a way to precisely figure out the loss but you can measure that with a thermometer and a cooler and evaluating how quickly the pump changes the tempurature of a small body of water, or measuring it's unloaded amp draw at a given voltage.

But what's probably easier is to assume that since a professional swashplate pump with ideal materials runs in the upper 90% efficiency range, then a hobby built pump is probably in the range of a steel gear pump, around 85% efficient. That gives you the multiplier 1456 which is a fun number to punch into a calculator and easily remembered.

Use that in the hydraulic equation and I'm guessing you should be pretty safe. At least here, wasted energy heating the working fluid is desirable vs a hydraulic system

 

[Toymaker]

Real world is a bustard.

I'd go oversized on the motor, so it has the ability to self cool while staying away from it's SF rating.

Good news that the pump is working well. At least, it sounds like, you could run the pump in at the lower pressure and lower rpm and either end up with it already for real duty or at least identify any future failure modes.

I really, really, really hate having to use this 5.3 Kg monster,....but with it's 1 kW power output, I'm 99% certain it has more than enough power. This is the same size motor I used on the 3 piston pressure washer, which develops higher pressure and flow rate. I also know it will run continuously without over-heating. I just wish it weren't so big and heavy.

AliExpress predicts delivery from 09 to 14 Aug,...hope they're right.

 

[Toymaker]

I ran a few measurement tests using the small 300 watt motor driving the pump. At open flow, the motor will spin at 2060 rpm and output 5 LPM. Below I've listed the 4 test points which I measured:

Pressure (psi)	RPM	Flow (Liters Per Minute)
100	760	1.35
100	1490	3.33
200	1060	2.19
250	966	1.88

Although this motor will produce 300 psi and more, it starts getting quite hot at pressures above 250 for sustained operation. I believe this motor would run for many hours producing 250 psi at 1.88 LPM.

 

[The Ignoble Troll]

I ran a few measurement tests using the small 300 watt motor driving the pump. At open flow, the motor will spin at 2060 rpm and output 5 LPM. Below I've listed the 4 test points which I measured:

Pressure (psi)	RPM	Flow (Liters Per Minute)
100	760	1.35
100	1490	3.33
200	1060	2.19
250	966	1.88

Although this motor will produce 300 psi and more, it starts getting quite hot at pressures above 250 for sustained operation. I believe this motor would run for many hours producing 250 psi at 1.88 LPM.

Do you happen to have the motors wattage consumption to work out efficiency?

Do you think you have enough flow to gently test the boiler and give that turbine a wet run?

Forgive my porridge memory, have you built the blower to couple to the turbine?

Still watching with great interest.

 

[Toymaker]

Do you happen to have the motors wattage consumption to work out efficiency?

Since I will be replacing the 300 Watt motor I used for these tests, with a 1 kW motor, which I hope will be the final version, I did not take voltage, current, nor PWM duty cycle measurements.

Do you think you have enough flow to gently test the boiler and give that turbine a wet run?

The general rule-of-thumb for monotube boilers, (as I understand) is the feed pump needs to be able to deliver 130% of the boiler's steam output pressure. If I keep boiler pressure below 150 psi, then feed pump pressure would be limited to 195 psi, which I believe the current 300W motor could manage. BUT, package tracking indicates the 1 kW motor should arrive today, so I will wait for the larger motor.

Forgive my porridge memory, have you built the blower to couple to the turbine?

My planned first live-steam tests are to spin the Tesla-Impulse turbine which I've connected to a 500 Watt PM brushed spindle motor. When spun by the turbine, the motor will act as a DC generator and provide a convenient means to measure it's output voltage across various resistive loads thereby providing power generated by the turbine. These initial test results will determine my next steps; hopefully, the 500W motor/generator will prove to be far too small and I will need to move to a much larger generator; I started with this motor/generator because it's what I have on-hand.

Still watching with great interest.

 

[Toymaker]

Goals achieved !! At the beginning of this thread I stated that I wanted to develop a feed water pump that could deliver 3 LPM at 600 psi. Today's tests came close enough to both of those goals that I'm claiming victory

The pic below shows the pump attached to a 1kW 36vdc motor rated at 3000 rpm.

Listed below are a few pump-motor operating points which were tested. (note that the PWM motor driver overheated and shut itself off at outputs over 60%; just to be on the safe side, I'll order a bigger driver for future use). I also need to swap out the wires leading to the motor from the PWM driver with heavier wires, as I had not planned on needing such a large motor.

PWM Display (%)	Output Pressure (PSI)	RPM	Flow Rate (LPM)
10	100	185	0.25
15	100	375	0.33
30	100	870	1.9
43	600	700	1.26
60	600	1300	2.73
60	900	1150	2.3

 

[Toymaker]

I successfully pressure tested the boiler using my new home-built, 9 piston pump. This test demonstrated the new pump was capable of pressurizing the boiler to several different pressure points, up to 600 psi. The below pic shows the output plumbing of the boiler; the valve is used to slowly close the steam output thereby allowing the pump to build pressure in the boiler tubes. The burner was not used for this test, only the new pump.

The following short video shows a pressure test of 500 psi; the analog dial pressure guage is shown first, then I quickly pan over to the digital display to record the input and output pressure sensor readings, then back to the dial guage. Throughout several different pressure tests, the digital sensors consistently displayed lower readings compared to the dial guage.

I also need to work on better vibration isolation,...the pump is nearly quiet inside my house, but as the video reveals, it's quite loud when placed on the test stand.

 

[The Ignoble Troll]

I successfully pressure tested the boiler using my new home-built, 9 piston pump. This test demonstrated the new pump was capable of pressurizing the boiler to several different pressure points, up to 600 psi. The below pic shows the output plumbing of the boiler; the valve is used to slowly close the steam output thereby allowing the pump to build pressure in the boiler tubes. The burner was not used for this test, only the new pump.

View attachment 159008

The following short video shows a pressure test of 500 psi; the analog dial pressure guage is shown first, then I quickly pan over to the digital display to record the input and output pressure sensor readings, then back to the dial guage. Throughout several different pressure tests, the digital sensors consistently displayed lower readings compared to the dial guage.

I also need to work on better vibration isolation,...the pump is nearly quiet inside my house, but as the video reveals, it's quite loud when placed on the test stand.

View attachment 159009

Thats a pretty awesome feat, successfully building a swashplate pump and having such a smooth output.

Nice work!

 

[Toymaker]

Thats a pretty awesome feat, successfully building a swashplate pump and having such a smooth output.

Nice work!

Thanks for the kind words. I'm super happy with the operational range & performance of my little pump. One of two main reasons I built this pump was because the pressure washer pump I was using could not be regulated at low flow rates,...the DC motor would stall and stop at low flow rates. My home-built pump delivers over 100 psi at very, very low flow rates. The second reason to build this pump is the need to be able to pump "hot-well" water, which will be close to 100 deg C, which this design should handle.

However, my pump is not perfect, it does leak a tiny amount of oil into the feed water. I suspect the source is coming from the oil left on the cylinder walls each time a piston draws in feed water; the round shape of the O-rings on each piston were not designed to scrape oil off of contacted surfaces.

 

[The Ignoble Troll]

Thanks for the kind words. I'm super happy with the operational range & performance of my little pump. One of two main reasons I built this pump was because the pressure washer pump I was using could not be regulated at low flow rates,...the DC motor would stall and stop at low flow rates. My home-built pump delivers over 100 psi at very, very low flow rates. The second reason to build this pump is the need to be able to pump "hot-well" water, which will be close to 100 deg C, which this design should handle.

However, my pump is not perfect, it does leak a tiny amount of oil into the feed water. I suspect the source is coming from the oil left on the cylinder walls each time a piston draws in feed water; the round shape of the O-rings on each piston were not designed to scrape oil off of contacted surfaces.

Have you tried a heavier oil yet?

 

[Toymaker]

Have you tried a heavier oil yet?

No, I have not yet tried a heavier weight oil,...but I do need to

Edit: I'm currently using ISO-68 Hydraulic Oil.

 

[The Ignoble Troll]

By chance is that "ways oil" you are using?

Hydfaulic oil is probably a good choice as it's non detergent.

Off the shelf air compressor oil might work. It's typically single weight iso-100 aka sae- 30 weight. Compressor oil, not air tool oil.

It'll also be non detergent.

 

[Toymaker]

By chance is that "ways oil" you are using?

Hydfaulic oil is probably a good choice as it's non detergent.

Off the shelf air compressor oil might work. It's typically single weight iso-100 aka sae- 30 weight. Compressor oil, not air tool oil.

It'll also be non detergent.

Here's a pic of what I'm using. The plastic bottle says it's ISO-68 Hydraulic oil, which Google searches tell me is a middle weight oil meant for heavy equipment use.

 

[The Ignoble Troll]

Ways oil for your lathe and mill is the same stuff, #2 ways oil.


I was just wondering if you were repurposing #2 ways oil which is ISO-68.

 

[Toymaker]

To give readers an idea of how small this pump is, here's a few pics of just the pump, without the electric motor.