# Solenoid (also vibration and ULKA) pump theory

Discussion in 'General Electronics Chat' started by ahto555, Mar 1, 2012.

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1. ### ahto555 Thread Starter Member

Mar 12, 2009
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0
Please help me understand theory behind solenoid pumps (also known from Italian brand name ULKA) used in espresso machines for example.
These pumps are AC and rated at 220V, 110V and even 24V. The same time I know rectifier diode is connected series with pump coil so that negative half period is basically cut off. 220VAC sinus peak-to-peak is close to 300V so half of it is 150V. Does it mean I can use 150V DC pulsed (50% on/50% off/50 Hz) to drive 220 VAC solenoid pump? Does it mean even lower DC voltage could be used because squere pulses have longer on time compare to sinusoid? Does it mean I could regulate pressure and flow by changing pulse frequency slightly (lets say 30-60 Hz)?

2. ### IanFiTheDwarf New Member

Mar 8, 2011
2
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Strangely enough I am looking to drive a vibratory pump with pulled dc for a car water injection system.

The RMS voltage of an AC supply is 0.707 x the peak voltage not the peak to peak, therefore a half cycle of a 240v AC supply will have a peak voltage of 240 / 0.707 or about 339.5v.

But the whole point of using RMS is it better describes the actual energy of the whole cycle so that we can assume that in most applications the RMS voltage will give the same power as the same DC voltage

With this type of pump this will be slightly different as a square pulse will accelerate the piston faster at the start and not tail off at the end but I don't think it will make a massive difference in practice.

So basic you will need to pulse a 240v AC pump with 240v dc to get the same results.

You should be able to reduce the output pressure and flow by several methodes, reducing the voltage or pulse width will reduce the distance the piston moves against a given pressure reducing output but will probably be quite hard to control. Reducing the number of pulses per second will work well up to a point when the output pressure and flow will pulse noticeably but is defeat going to be the easiest to achieve.

In my application I have to power the plump from a 12v supply so I will need an invertor. I am thinking of either modifying an of the shelf inverter or just rectifying then pulsing the output

3. ### ahto555 Thread Starter Member

Mar 12, 2009
11
0
Thank you!

need it also for automotive application so powering from 12VDC (9...14,5VDC).
I would like to use it as ethanol conversion cold start aid pump where small amount of gasoline is injected into intake manifold during cranking and shortly after. To get very fine mist and wide hollow cone spray pattern a lot of pressure is needed.
I have EX5 model E 230 VAC (48W) ULKA pump and small cheap 100-200W TL494 based Chinese power inverter I played with. The problem was very long lag time. It was close to 5 seconds from powering inverter up to pump start. So not good for my application. The lowest voltage vibration pump I have found is 24VAC (here for example - http://www.ebay.de/itm/Pumpe-Ulka-E...aschinen_MW&hash=item1e63c29d65#ht_2159wt_940).

I can see one problem with your application. These pumps are not intended for continuous work. Label clearly states 2/1 min which means 2 minutes working and 1 minute rest.

4. ### Wendy Moderator

Mar 24, 2008
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The All About Circuits forum Administrative Team has elected not to host discussions of automotive electrical system modifications/enhancements due to safety concerns, the potential of legal ramifications and the possible circumvention of vehicle regulations at the state and federal level.

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