Device Setup
January 2023
•
Rev. 0
• Standard Devices User Manual
25
STP/NTP Reference Values
Mass Flow Devices
MENU
→
SETUP
→
Sensor
→
STP
Flow Ref
or
NTP Flow Ref
A mass flow device references a given temperature and
pressure combination to calculate flow. Standard mass flow
uses an STP (standard temperature and pressure) reference
point and normal mass flow uses an NTP (normal temperature
and pressure) reference point. Depending on the engineering
units selected, either STP or NTP will be editable from this
menu. For example, if SLPM (Standard liters per minute) is
selected, STP is editable. If NLPM (normal liters per minute) is
selected, NTP is editable.
Reference options:
•
Stan T
:
Standard Temperature
•
Stan P
:
Standard Pressure
•
Norm T
:
Normal Temperature
•
Norm P
:
Normal Pressure
•
Ref temp units
changes the temperature
units used for STP and NTP calculations.
•
Ref pressure units
changes the pressure
units used for STP and NTP calculations
Unless otherwise requested, your flow controller ships with
a default STP of 25°C and 1 atm (which affects flow units
beginning with “S”), and an NTP of 0°C and 1 atm (which affects
flow units beginning with “N”).
!
Caution:
Changes to STP or NTP references
alters your mass flow readings.
Flow and Pressure Averaging
MENU
→
SETUP
→
Sensor
→
Flow Averaging
MENU
→
SETUP
→
Sensor
→
Pressure Averaging
Averaging the flow over a longer time may be useful in
smoothing fluctuating readings. This menu changes the
time constants of the geometric running averages for flow
and pressure. Values roughly correspond to the time constant
(in milliseconds) of the averaged values. Higher numbers
generate a greater smoothing effect. The device is capable
of a maximum 255 ms.
Zero Band
MENU
→
SETUP
→
Sensor
→
Zero Band
The zero band threshold is an amount of flow or pressure
under which measurements are displayed as 0. The maximum
zero band is 6.38%. For example, a 20 SLPM controller with a
zero band value of 0.25% displays as 0 SLPM for all readings
below 0.05 SLPM. This function also applies to gauge pressure
readings when using the optional barometer.
Totalizer Options
Flow Devices
The totalizer measures the total flow over a given time and
is one of the display screens. For more information on the
totalizer display, see
.
Totalizer Mode
MENU
→
SETUP
→
Sensor
→
Totalizer
→
Totalizer 1
or
Totalizer 2
→
Mode
All devices have 2 options for calculating flow:
• Positive Flow Only:
The totalizer only counts
flow that passes left to right through the flow body
of the device. If any negative flow (right to left)
moves through the system, it is not counted.
• Reset After No Flow:
When flow is completely
stopped, the totalizer holds the current value
of the measured flow until flow begins again.
Once flow begins, the totalizer resets to zero.
Bidirectional dual valve controllers can have 2 further options
for calculating flow:
• Negative Flow Only:
The totalizer only counts negative
flow (flow that passes right to left through the flow body
of the device). Positive flow (left to right) is not counted.
• Bidirectional:
The totalizer adds flow that
moves positively through the system and
subtracts flow that moves negatively.
Totalizer Limit and Format
MENU
→
SETUP
→
Sensor
→
Totalizer
→
Totalizer 1
or
Totalizer 2
→
Limit and Format
The totalizer can report up to a maximum of 10 digits. By
default, it uses 7 digits and the placement of the decimal is
the same as the live flow rate.
The limit of the totalizer sets where the decimal is placed
in the total amount of measured flow. Most devices can
be configured to measure to the hundredths position. It is
possible to limit measurement to a length of time. The options
allow for as little as 10 minutes to as long as 10 years. When
set, the totalizer measures the flow for that length of time and
then stops until reset. How the totalizer reacts is based on
the
Totalizer Limit
settings.
Configuring the zero band.
Adjusting the flow averaging
time constant.
Totalizer options.
Totalizer
Limit and
Format
screen.