Ulka EX5 vs EX4.

[symphonie]

Hi folks,

I've got an 7 year old HX machine (BFC Junior Semi) at home whose internal vibe pump's on the way out, I think its using an Ulka EX5 or similar model. As the machine does not have a preinfusion chamber in the e61 brew group (Solenoid activated not lever). I was thinking of getting an Ulka EX4 instead for replacement as it has a much slower pressure build up compared to the EX5 and therefore achieving kinda passive preinfusion.

Do you think it might be worth it to try at all?

[metho]

Both pumps seem to be similar classes of Ulka pumps. See attachment. I don't think that it would make a significant difference. The greatest difference would be if the pumps are made for different voltages. Say 220V vs 240V. Noting that I have seen 50Hz ULKA pumps made in three different voltages (220V, 230V, 240V) in different Lelit type machines; I don't think it matters in Australia with 230V +10%/−6% tollerance. I assume the greatest issue would be a 240V Ulka pump model producing less pressure/volume than expected. However since most machines have OPVs that dump the excess pressure anyway, I would not be too concerned with a 240V model in Australia.

[MrJack]

Hi folks,

I've got an 7 year old HX machine (BFC Junior Semi) at home whose internal vibe pump's on the way out, I think its using an Ulka EX5 or similar model. As the machine does not have a preinfusion chamber in the e61 brew group (Solenoid activated not lever). I was thinking of getting an Ulka EX4 instead for replacement as it has a much slower pressure build up compared to the EX5 and therefore achieving kinda passive preinfusion.

Do you think it might be worth it to try at all?

Something to consider, looking at the pump curves (Ulka E models), the E4 has a dead-head discharge pressure of nearly 22 barg (vs. 16 barg for the E5). It's probably fine, but it is possible there might be a concern about exceeding the design pressure of the system.

Other than that, there should be a decrease in flow at minimum pressure, but I don't think going from 600 mL/min to 400 mL/min is going to achieve the slow pre-infusion you're expecting...

If you want pre-infusion, put in the EX5, and then put in a needle valve in parallel to the OPV bypass (or downstream of the pump). Works well!

[symphonie]

Something to consider, looking at the pump curves (Ulka E models), the E4 has a dead-head discharge pressure of nearly 22 barg (vs. 16 barg for the E5). It's probably fine, but it is possible there might be a concern about exceeding the design pressure of the system.

Other than that, there should be a decrease in flow at minimum pressure, but I don't think going from 600 mL/min to 400 mL/min is going to achieve the slow pre-infusion you're expecting...

If you want pre-infusion, put in the EX5, and then put in a needle valve in parallel to the OPV bypass (or downstream of the pump). Works well!

Thanks for the info mate, only heard of needle valves used in slayer. don't know how hard it'd be retrofitting one into the machine. need to look into it.

[MrJack]

It will depend on your machine and your skillset

I fitted one to my BZ99s - still figuring out what I think of the result.

[symphonie]

It will depend on your machine and your skillset

I fitted one to my BZ99s - still figuring out what I think of the result.

Any pics to share if you don't mind?

[MrJack]

Any pics to share if you don't mind?

Just one at the moment. Plan to do a bit of a write-up when time permits.
https://www.instagram.com/p/BKIiEowBNK2/

[bluey]

According to Ulka documentation, the main difference is the E-4 is designed to be quiet. 58dB vs 64dB for E-5.
Ulka E series EP-7

EP plastic, EX brass. EX4 is not listed on Ulka site.

[symphonie]

Agreed, I have already replaced EX5 with EX4, Noise/vibration has dropped significantly and the pressure ramp up is a lot slower which is good. don't think I will go back to EX5 again.

According to Ulka documentation, the main difference is the E-4 is designed to be quiet. 58dB vs 64dB for E-5.
Ulka E series EP-7

EP plastic, EX brass. EX4 is not listed on Ulka site.