The late great Jim Walker was actually the first to commercialize a presssure tank that consisted of a bladder but the bladder was not pressure filled. Instead it had two boards on each side and rubber bands were slipped around the outside. This allowed some adjustmeni of head pressure by adjustment of the number of rubber bands. The real secret of the success with this system was however because Mr Jim saw fit to design a clever for real pressure regulator into the system therefore avoiding the sensitive needle syndrome completely.

John