Biogas Operating Manual
Page 10
Geotechnical Instruments (UK) Ltd
BMUK0001 / Issue 1
You can do this by pressing key
to re-set the reading procedure or by pressing
store reading.
Either option allows a new reading sequence to begin.
2. At this point connect the sample tube (with water trap) from the sample point to the inlet port of the
instrument, ensuring the connector ‘clicks’ into place. If using a gas pod, it should plugged-in to
external port 1 and connected to the outlet of the instrument. At this point you will see the system
pressure reading change as it responds to the pressure on the inlet hose. It is important to
remember that the system pressure reading is only active during this initial phase. After the pump
is activated or if the user presses
measure flow or
store reading the system pressure is
frozen until the next reading cycle has begun.
3. Pressing
the pump key draws a gas sample into the instrument. You should see the main gas
readings start to change. It is recommended to run the pump until the gas readings have stabilised
(typically 30 seconds) using the counter provided. If you are only interested in the main gases
pressing the
store key now would record these values and re-start the reading cycle. Note…If
you have enabled gas alarms a flashing bell symbol may be displayed next to the appropriate gas
reading value if a pre-set alarm condition has been passed.
4. Assuming you have selected a flow device (via instrument settings) press key
to take a flow
reading. At this point you should see a brief message confirming that the gas readings have been
fixed (i.e. stored temporarily). Depending on which flow device you have selected the operation
may vary. For example if you have no flow device selected then you will not have a key
option,
pressing the
store key will store the currently displayed data to memory.
5. If enabled (via instrument settings) you will be prompted to enter a temperature reading or attach a
temperature probe. If you are not using an external gas pod you might want to disable this option.
You can then plug a temperature probe in to external port 1 (in place of the gas pod) at the start of
the reading cycle. The temperature reading is then displayed on the main gas screen and will be
frozen when key
is pressed to start the flow measurement phase. Otherwise simply follow the
on-screen instructions to record a valid temperature reading either by attaching a probe or
manually entering the temperature recorded using a third party sensor. If no temperature is
available then 20 degrees centigrade is assumed for the subsequent flow calculations.
6. If you have selected either pitot tube or orifice plate as your device type you will now be asked to
zero the static and differential pressure transducers. It is possible to skip this stage but it is
important to zero the transducers for repeatable results especially on very low flows. To zero the
transducers simply follow the on-screen instructions. Remember you will have to disconnect the
hoses from the sample point and wait a few seconds for the readings to stabilise before zeroing.
You will then be returned to the main read screen where the flow calculation will be displayed along
with the current static and differential pressures. You will also be able to review the Orifice and
pipe diameter that are currently selected. These can be changed (via instrument settings) if
required. Once the flow reading has stabilised simply press store
to record the reading.
7. If you have selected an anemometer as your device type there is no need to zero the transducers
and this stage is skipped automatically. You be returned directly to the main read screen where the
velocity and flow will be displayed along with the currently selected pipe diameter (required for a
valid flow calculation). The anemometer should be plugged into external port 2 on the instrument.
After it has been correctly inserted into the sample point, allow the flow reading to stabilise and
press store
to record the reading.
8. If you have selected user input as your device type you will be prompted to enter a flow reading
manually. After typing in the flow reading you can return to the main reading screen and the flow
measurement you entered will be displayed. Press store
to complete the reading.
9. After
the store key is pressed and if enabled (via instrument settings) you will be prompted to
enter an 8 character identification code for the current reading set. This is done by using the
cursor keys to navigate around a grid of alphanumeric characters. The
enter key is used to
select each character as required. Key
is used complete the process and exit this screen. At
anytime the
backspace key can be used to erase any selected characters if required.
