Electronic proportioner using continuous metering and correction

摘要

The controller of the plural component proportioner (10) dispenses both components (or all three if a three component material) simultaneously (at least initially) and maintains ratio at the end of each predetermined volume of material by determining which component pump (12) has reached the desired amount of travel (given the resolution available) and using a valve (16) to shut off output of that pump until the other side has caught up. At pump changeover, the output valve for that pump (12) is shut off and the air motor (12a) allowed to run until travel stops to account for cavitation, air entrainment, compressibility, or poor inlet check performance.

主权项

1. A method for preparing to pump a first fluid that is originally compressible, comprising:
providing a first positive displacement pump having:
a first check valve;a first displacement transducer;a first outlet; anda first controllable valve at the first outlet that when closed stops the first fluid from flowing through the first outlet; closing said first controllable valve; intentionally engaging the first pump after the closing of the first controllable valve to compress the originally compressible first fluid and to build up pressure opposing the first pump; closing the first check valve after the first fluid is compressed; taking a first reading from the first displacement transducer when sufficient pressure has built up to cause the first pump to stall; keeping the first check valve closed; and using the first reading as a starting location for the first pump prior to opening the first controllable valve to permit the first fluid to flow from the first outlet.