HT-1 Controller Systems
The HT-1 is PULSAIRs mixing system for single horizontal tanks . The HT-1 system can mix in a horizontal tank with the same efficiency and effectiveness that an FT-1 has in a Flat Bottom Tank. The HT system is identical to the FT system except for the accumulator plate arrangement. (See PULSAIR Horizontal Tank Systems.) The HT system usually has a single row of plates along the longitudinal axis of the tank bottom.
The HT-1 Controller has one input and three outputs. The controller requires an input supply of compressed air or gas. The minimum pressure required to operate the controller is 50 psi. The control circuitry has its own pressure regulator that is factory set at 60 psi. There should be no need for field adjustment, although, the regulator control knob is on the right side of the relay panel inside the controller. There is also a port available where a pressure gauge can be connected to read this pressure. Customers needing to readjust the pressure will be supplied with the proper fitting and gauge for reading and adjusting the pressure. (Contact PULSAIR World Headquarters in Bellevue, WA, USA.) The three outputs are:
1) A variable pressure signal to the injection regulator that sets the injection pressure.
2) A pilot signal to the center injection valve.
3) A pilot signal to the radial injection valve(s).
The controller sends an air signal (pilot signal) that acts on the spool in the injection valve causing the spool to shift to the open position. In the open position the valve allows air to flow to the accumulator plate(s). The pilot signal is then vented to the atmosphere. As the pressure drops, the injection valve closes, cutting off the flow of air to the accumulator plate(s).
The controller sends an air signal (pilot signal) that acts on the spool inside the injection valve causing it to move into the open position. Once open, the valve allows air to flow to the accumulator plate(s). The pilot signal is then vented to the atmosphere. As pressure is lowered, the injection valve closes, cutting off the flow of air to the accumulator plate(s).
The Injection Time control determines how long the the pilot signal is on. The longer this signal is on, the longer the valve will stay in the open position. The Dwell control determines the amount of time between injection pulses.
Note: the distance between the injection valve(s) and the controller also affects the amount of time that the valve will remain open. Air is elastic. If the injection valve is a long distance from the controller then a longer pulse signal is required to open the valve because the volume inside the tubing must be filled with air before there is sufficient pressure to open the injection valve. The pilot signal must fill the tubing and increase the pressure from zero to the injection pressure before the valve will open. Conversely, to close the valve the air must be exhausted from the tubing. The longer the tubing the longer it takes to exhaust the air. The net effect of excessive distance (more than 20 feet), between the valve and controller will make the injection valves on- off cycle slow, sluggish and diminish it effectiveness.
PULSAIR installation manuals recommend that the controller and injection valves be located next to each other. This allows for a shorter pilot signal tubing and therefore a very responsive injection valve. A quick acting injection valve produces a sudden burst of air under the accumulator plate. This burst of air causes a shock wave that excites all the liquid molecules in the tank. One of Newtons laws states that "things in motion tend to stay in motion". Therefore, when the bubble starts to rise in the liquid it is working with liquid that is already in motion because of the initial shock caused by the bubbles formation. The combination of the shock and vertical motion is why PULSAIR is so effective. It is also why the entire contents of a tank are in motion after only one to two pulses. (See Intermittent Mixing)