Main – Alicat M Series Mass Flow Meter User Manual

Page 15

MAIN

This mode defaults on power up, with

mass flow as the primary displayed

parameter.
The following parameters are displayed in

the Main mode.
Gas Absolute Pressure: This sensor

references hard vacuum and reads

incoming pressure both above and below

local atmospheric pressure. This parameter

is moved to the primary display by pushing

the button above PSIA.
The engineering unit associated with

absolute pressure is pounds per square

inch absolute (psia). This can be converted to gage pressure (psig) by subtracting

local atmospheric pressure from the absolute pressure reading:

PSIG = PSIA – (Local Atmospheric Pressure)

Gas Temperature: M-Series flow meters

measure the incoming temperature of the

gas flow. The temperature is displayed

in degrees Celsius (°C). This parameter is

moved to the primary display by pushing

the button above °C.
Pushing the button again allows you to

select 0C (Celsius), 0K (Kelvin), 0F (Fahrenheit)

or 0R (Rankine) for the temperature scale.
To select a temperature scale, use the LN-UP

and LN-DN buttons to position the arrow in

front of the desired scale.
Press SET to record your selection and return

to the MAIN display. The selected temperature scale will be displayed on the screen.
Tare: Pushing the TARE V button tares the flow meter and provides it with a

reference point for zero flow. This is an important step in obtaining accurate

measurements. It is best to zero the flow meter each time it is powered up. If

the flow reading varies significantly from zero after an initial tare, give the unit a

minute or so to warm up and re-zero it.
If possible, zero the unit near the expected operating pressure by positively blocking

the flow downstream of the flow meter prior to pushing the TARE button.

Zeroing the unit while there is any flow will directly affect the accuracy

by providing a false zero point. If in doubt about whether a zero flow

condition exists, remove the unit from the line and positively block both ports

before pressing the TARE button. If the unit reads a significant negative value

+21.50

+0.000

CCM

TARE V

PSIA

+13.60

+0.000

SCCM

LN-DN

CANCEL

SET

MODE

>#C
#K
#F
#R

LN-UP

SCCM

Air

+0.00