Hydrazine Flowmeter Calibration

A flow loop was designed which addressed the testing and validation needs of a customer involved in the development of a hydrazine flowmeter for use on an orbital platform. Data acquisition and control software was internally developed. The system performed flawlessly when deployed. The desired test regime was successfully completed and the data delivered to the customer.

Due to the health hazards and high reactivity of hydrazine, the system was designed to meet stringent safety requirements. A continuous helium purge and bubble scrubber were included in the design. All electrical connections and enclosures were helium purged. The test stand was operated remotely from a safe distance. All functions were controlled from the remote test station, and operation and diagnostics could be carried out without a need to approach the test stand.

A comprehensive procedure was developed for the safe setup, operation, and take down, of the system. The procedure addressed the requirements of the customer and test facility, and obtained the final approval of all involved parties.

Measurements performed by the system included flow rate, pressure, multiple temperatures, and the multiple analog voltages and serial data streams from the two units under test. All of the raw, unprocessed data was time stamped and archived to enable independent validation by the customer. Analog data was logged at 20Hz. Turbine flowmeter pulse timing and UUT serial data was logged immediately upon arrival.

All measurement hardware was independently calibrated, and calibration certificates were provided to the customer. Highly accurate flow rate calculations were made possible by taking the effect of viscosity and density variations of the fluid into account.

The internally developed control software allowed both manual and fully automatic test modes. Automatic mode was designed to keep procedural error from affecting test results, and to allow the operator to spend time simply monitoring the system for safe operation and unexpected occurrences, rather than getting bogged down in complicated test procedures. In automatic mode, flow rates and durations were pre-programmed. The computer tightly controlled pump speed in order to match desired flow targets. The system would put itself into a safe state if the computer or operator initiated shutdown. Also, an inherently safe state was achieved in the event of power loss or control interruption.

Testing was successfully conducted at an industrial test facility over the course of three days, and test data was delivered to the customer on the spot.