Hello Harley,

In reply to you post here:
http://www.rcuniverse.com/forum/fb.asp?m=9377896

Thank you for the feedback. I have added that in the beginning of this post.

The BVM UAT was a fantastic upgrade from previous header tank with a filter placed at the center of the the tank volume.
The great innovation was the buffering effect offered by the membrane bag.
The UAT has a usable volume of 3 oz ( ie the volume on the supply side of the membrane ) or 88 ml.

For a P-160SX @ 540 ml/min, this volumes equals to a theoretical buffering effect of 10 seconds ( ie if the UAT is disconnected form the supply line, the engine will shut down after 10 seconds ).
For the P-200SX @ 730 ml/min the UAT offers a buffering of 7 seconds. I found out that on Jetcat engines, a buffer effect of 6 seconds is a minimum.

The problem is that if the suction side does offer too much resistance, the UAT will start to get vacuumed because of its soft nature.
The P-160SX will deflate the tank moderately by about 30% and the buffer effect will drop to 7 seconds in the worst cases. This remains acceptable.
However, on a non perfect installation, a P-200SX could vacuum the UAT to less that 50% of its capacity. The bag remaining mostly unaffected by the vacuum effect, the usable buffer volume will shrink so much that the buffering could drop to less than 3 seconds.

In that case, the membrane itself will start to cavitate.

One solution that BVM could offer, could be to include a slightly larger glass fiber ( ie transparent enough material to clearly see the fuel level ) rigid UAT tank along with the plastic one in their UAT kit, thus offering the possibility for the customer to choose between a low flow and a high flow application. The term "Universal" of the UAT name will be reinforced.