Sierra 730 - Manual (Page 5)

Series 730 Instruction Manual
IM-73-E 3
Series 730 Mass Flow Meters
Sierra’s Series 730 Accu-Mass
™
Flow Meters provide outstanding
measurement accuracy and fast 200 millisecond response time. The
meters monitor the mass flow rate of air and process gases in ranges
from 0 to 250 scfm. They are available in pipe sizes from 1/4-inch to
3 inches. Accu-mass meters are ideal for monitoring flows of non-
corrosive gases compatible with the device’s wetted materials and ap-
plications requiring fast time response.
Sierra’s Accu-Mass sensor is a reference-grade platinum resistance
temperature detector (RTD) encapsulated in glass. The platinum RTD
wire is wound on a rugged ceramic mandrel for strength and stability.
The sensor is located at the tip of a 304 stainless steel probe which is
inserted in the gas stream. The sensor consists of two sensing ele-
ments–a velocity sensor and a temperature sensor which automati-
cally corrects for changes in gas temperature. When power is applied
to the flow meter, the transducer electronics heats the velocity sensor
to a constant temperature differential above the gas temperature. The
cooling effect of the air as it passes over the heated sensor is meas-
ured by the bridge voltage. The meter electronics converts this volt-
age into a linear 0-5 VDC, 0-10 VDC, or 4-20 mA output signal.
The meter electronics are packaged in an anodized aluminum NEMA
2 or a painted cast aluminum NEMA 4 enclosure. The electronics are
mounted either directly on the sensing probe or for NEMA 2 enclo-
sures, remotely up to 100 feet (60 meters) away.
Gas temperature sensor
Heat
Heated velocity sensor
Accu-Mass™ Sensor
Mass flow
Figure 1. Series 730 Accu-Mass Sensor Probe