Fluid Components International MT91 Troubleshooting

CHAPTER 5 - TROUBLESHOOTING FLUID COMPONENTS INTL

5. Troubleshooting

Quick Check

Use Table 5-1 as a quick check of problems and solutions. More in-depth discussions follow this table.

No Display or Dim Display Adjust potentiometer R1 (located on display board) clockwise (10 turns

Display is locked up Cycle the input power or press any key for more than 10 seconds.

Incorrect Readings Verify that all ribbon cables are firmly seated. See Figure 2-3 and 2-4.

Warning:

Caution:

Problem Solution

No Display Check fuses. Verify correct power is applied.

Only qualified personnel should attempt to test this device. The operator assumes all
responsibilities for safe practices while troubleshooting.

The flow transmitter contains electrostatic discharge (ESD) sensitive devices. Use standard ESD
precautions when handling the flow transmitter. See Chapter 2, Installation for ESD details.

Table 5-1. Quick Check Troubleshooting

Verify the ribbon cable between the backplane board J18 and the display J1 is
solidly connected and the red stripe is at pin 1. See Figures 2-3 and 2-4.

maximum) until display appears. See Figures 2-3.

Non-maintenance Observations

At this point, simply observe the system setup to verify operation. No disassembly or testing is required at this time.

Check Serial Numbers

Verify that the serial number of the flow elements and the flow transmitter are the same. The flow elements and the
flow transmitter are a matched set and cannot be operated independently of each other.

Check Input Power

Verify that the correct power source is turned on and connected.

Check the Unit Installation

Review the information on instrument installation in Chapter 2 to verify correct mechanical and electrical
installation. Verify that all ribbon cables are seated firmly.

Relay Output Board J1 Þ Backplane Board J21 and/or J22
Analog Output Board J1 Þ Backplane Board J19
Display Board J1 Þ Backplane Board J18

Check for Moisture

Check for moisture on the flow transmitter. Moisture on the flow transmitter may cause intermittent operation.

Doc. No. 003185 Rev. B 5 - 1

Model MT91 Multipoint Flowmeter

FLUID COMPONENTS INTL CHAPTER 5 - TROUBLESHOOTING

Check Application Design Requirements

Application design problems usually occur with first time application units, although the design should also be
checked on units that have been in operation for some time. If the application design does not match field
conditions, errors occur.

1. Review the application design with plant operation personnel and plant engineers.

2. Ensure that plant equipment such as pressure and temperature instruments conform to the actual conditions.

3. Verify operating temperature, operating pressure, line size, and gas medium.

Verify Standard Versus Actual Process Conditions

The flowmeter measures the mass flow rate. The mass flow rate is the mass of the gas flowing through a pipe per
time. Other flowmeters, such as an orifice plate or a pitot tube, measure the volumetric flow rate. The volumetric
flow rate is the volume of gass per time. If the readings displayed by the MT91 does not agree with another
instrument, some calculations may be necessary before comparing them. To calculate the mass flow rate, the
volumetric flow rate, and the pressure and temperture at the point of measurement must be known. Use the following
equation to calculate the mass flow rate (Standard Volumetric Flowrate) for the other instrument.

Equation:

=× ×

QQ

SA

A

T

A

S

P

S

P

T

Where:
QA= Volumetric Flow QS= Standard Volumetric Flow
PA= Actual Pressure TA= Actual Temperature
PS= Standard Pressure T

Standard Temperature

S=

and Pressure and Temperature are in absolute units.

Example:

QA= 1212.7 ACFM QS= 1485 SCFM
PA= 19.7 PSIA TA= 120°F (580°R)
PS= 14.7 PSIA T

1212.7 ACFM

( )

1

Troubleshooting Process

Verify Units

Observe the normal display screen to verify that the unit of measure for channel 1 and 2 are the expected units.
If units are correct, proceed to the next section. If units are not correct, refer to Chapter 3 for instructions on

selecting measurement units.

Verify Channel Assignment

If there is no reading or faulty reading, make sure that the sensing points are assigned to the correct channel.
Refer to Chapter 3 for instructions on assigning sensing points if they need to be assigned.

1. Go to menu level 2.2.1 and select the desired channel (SetupÞ OutputsÞ Assign Heads) .

2. Select 5=View Assigned. An ‘x’ will appear under the sensing point number if it is assigned.

70°F (530°R)

S=

19.7 PSIA

( )

580° R

530° R .

( )

14.7 PSIA

= 1485 SCFM

If the correct sensing points are assigned, continue with the next section.

Model MT91 Multipoint Flowmeter 5 - 2 Doc. No. 003185 Rev. B