[J. Domingos]

Hi, Guys...
in practical terms... who knows the difference between Ultratec HF4 4040 RO Membrane and
40" HF5-4040 Ultratec Ultra-Low Pressure
I'm dealing with a few issues on my cart, I made it...  

[mikecam]

Hi, Guys...
in practical terms... who knows the difference between Ultratec HF4 4040 RO Membrane and
40" HF5-4040 Ultratec Ultra-Low Pressure
I'm dealing with a few issues on my cart, I made it...  

The HF5 is designed to work at such "low" pressures as 70PSI as opposed to the HF4 needing about 90 PSI.

[Paul Coleman]

Hi, Guys...
in practical terms... who knows the difference between Ultratec HF4 4040 RO Membrane and
40" HF5-4040 Ultratec Ultra-Low Pressure
I'm dealing with a few issues on my cart, I made it...  

The HF5 is designed to work at such "low" pressures as 70PSI as opposed to the HF4 needing about 90 PSI.

So far, my HF5 has managed at a bit below 40PSI.  Not optimum, but acceptable.  70 - 95 litres per hour with outward TDS as low as 009.  When it was getting near time to change the  pre filters it was about 60 litres per hour at 015 but improved once I had changed it.  I suppose that the big test will be about how long the HF5 lasts.  Only about 8 months so far.
Tap TDS is around 200.

[J. Domingos]

So... in that case look's like this is the wrong RO for a cart working with a heavy duty pump.
Who knows what kind of RO membrane they use on those faster production carts Should be the HF4???