GE PT878GC Manual De Usuario

April 2004

Flowcell problems fall into two categories: gas problems and pipe 
problems. Read the following sections carefully to determine if 
such problems exist.

Gas Problems

Most gas-related problems can be solved by proper design of the 
flowmeter installation and the proper choice of transducer 
frequency. Contact GE Panametrics if you cannot solve a gas-
related problem.

If the physical installation of the system meets the recommended 
specifications, it is possible that the gas itself may be preventing 
accurate flow rate measurements. The gas being measured must 
meet the following requirements:

1. THE GAS MUST BE HOMOGENOUS, SINGLE-PHASE 

AND RELATIVELY CLEAN. Although a low level of 
entrained particles may have little effect on the operation of 
the TransPort, excessive amounts of solid or liquid particles 
will absorb or disperse the ultrasound signals. This 
interference with the ultrasound transmissions through the gas 
will cause inaccurate flow rate measurements. In addition, 
temperature gradients in the gas flow may result in erratic or 
inaccurate flow rate readings.

2. THE GAS MUST NOT EXCESSIVELY ATTENUATE 

ULTRASOUND SIGNALS. Some gases (i.e., high-purity 
carbon dioxide, hydrogen, helium, etc.) readily absorb 
ultrasound energy. In these cases an “E1” will appear on the 
screen to indicate that the ultrasonic signal is insufficient for 
reliable measurements.