MPB

Pergam MPB — Vehicle Methane Survey Manual

MPB2

1. What MPB is

MPB finds methane leaks from a moving vehicle. A laser measures the gas, a satellite receiver says where the vehicle was at that moment, and the software on the on-board computer brings the two together: a concentration, a position, a time, recorded several times a second for the whole working day.

The measurement is extractive. An intake on the bumper draws outside air along a tube into a sealed cell, and the laser measures the air that arrives there. So the reading is a concentration of the air the vehicle is driving through, in parts per million, and not a column integrated along a beam.

This matters for how the day is driven. Around 95% of a distribution network runs under the carriageway, so gas from a buried leak surfaces under the vehicle rather than beside it. The survey is one pass along the street, at working speed, and every metre counts once.

Note: MPB records what it measured and where. It does not say whose pipe a leak came from: what it hands over is a place to go and dig, together with the readings behind it.

2. Starting up

The order matters. The instrument is powered first and the software second, because the first thing the software does is look for the instrument on the network.

Switch on the instrument and wait for the pump to run.
Start MPB from the desktop icon.
The search screen appears and stays until the instrument answers. There is nothing to press.
When it answers, the startup screen opens and the warm-up begins.

The search screen

Looking for the MPB — Looking for the instrument. The line at the bottom is the useful one: it says whether the computer has the network address the instrument is reached at.

This screen is a question being asked over and over: the software broadcasts a search on the network and waits for the instrument to answer. Normally it lasts a couple of seconds.

Read the line at the bottom. Interface 169.254.0.1 detected means the computer is set up correctly and the silence is coming from the instrument — check power and cable. If instead it says the address is missing, the search is not even being sent: the network adapter has lost the fixed address and no cable in the world will help until it is back.

Careful: Do not unplug the Ethernet cable while MPB is running. The software goes on drawing the last reading it received for a few seconds before it notices, and those seconds go into the recording as if they had been measured.

3. The startup screen

This screen is the warm-up. The laser has to reach its working temperature and then find the methane absorption line, and neither is instant: from cold it takes a few minutes, and the vehicle should stand still while it happens.

MPB startup screen — The startup screen. The two bars are the warm-up; the plot is the absorption line the instrument is looking for; OK stays grey until it has found it.

What is on it

Item	What it is
The two bars	Progress. The first is the temperature settling, the second is the search for the absorption line. Both have to fill.
The black plot	The absorption line as the instrument sees it. A clean, steady shape means the laser is locked on.
Signal, mV	How much light is reaching the detector. It falls as the optics get dirty; a value far below the usual one is worth reporting.
Temperature, degree	The temperature the instrument is holding. It is what the first bar is working towards.
Repeat	Runs the warm-up again from the beginning. Use it if the plot never settles, or after changing the temperature mode.
OK	Goes to the main screen. It is grey and cannot be pressed until the instrument is ready; it then goes on by itself if nobody presses it.

Temperature mode

The cell is held at a fixed temperature, and that temperature has to be above the outside air — the instrument can heat but it cannot cool. There are three modes, and choosing one means choosing which working temperature the instrument will hold:

Mode	When to use it
Winter	Cold weather. The lowest of the three working temperatures, and the quickest to reach.
Summer	Ordinary warm weather. The usual choice for most of the year.
Supersummer	Real heat: a vehicle standing in the sun, a cabin well above thirty degrees. Only this mode stays above the air on such a day.

The symptom of the wrong mode is always the same: the first bar climbs and then sticks, or fills and falls back, because the instrument is trying to hold a temperature the surroundings will not let it hold. When that happens, move up one mode and press Repeat.

Tip: Let the software choose. Under Operating parameters settings there is Automatic temperature mode selection: with it ticked, MPB reads the temperature at start-up, compares it with the working temperature of each mode, picks the one that fits and restarts the warm-up by itself. On a vehicle that works in every season it is the setting to leave on.

Careful: Changing the mode changes the temperature the whole measurement is made at, so the warm-up starts again from the beginning. Change it before the round, not in the middle of one.

Sensitivity

Sensitivity runs from 1 down to 0.6, and it sets how readily the instrument declares that what it sees is gas rather than noise. It is a threshold inside the instrument, not a gain: it does not make small leaks bigger, it decides which small rises are worth calling a detection.

1 is the most sensitive. It finds the least gas and it also reports the most that turns out to be nothing.
0.6 is the steadiest. Fewer false calls, and a very small leak can pass unremarked.

Leave it where the instrument was commissioned. The two reasons to move it are a survey that keeps declaring detections on clean streets — go down a step — and a customer who wants the smallest possible leak found on a quiet residential round, where a step up costs only patience.

Note: Whatever is chosen here goes into the session file, so a day recorded at 0.8 can be told apart from a day recorded at 1 long afterwards. Do not change it in the middle of a day: the first half and the second half would no longer be the same survey.

4. The D N F lights

Three lights sit at the top of the screen, on the startup screen and on the main one. They are the quickest check that the day can go ahead, and they are worth a glance before pulling away.

The D N F indicators — Instrument, navigation, flow. Green on the left two and grey on the F of an instrument without the flow board is a normal picture.

Light	What it means
D	green: the instrument is connected and measuring. red: no answer from it — check the cable and the power.
N	green: a valid position. yellow: the receiver is working but has no fix yet. red: no receiver at all.
F	green: air is flowing through the cell. yellow: the flow is falling towards the alarm. red: change the air filter. grey: no reading at all.

Careful: A grey F is not a clean filter. It means nothing is being measured at all — the board is off, the sensor is unplugged, or the pump has stopped — and a stopped pump means the instrument is sampling nothing while the map goes on drawing a track.

The F light only appears on instruments fitted with the flow board. On the others it is not shown.

5. The main screen

This is the screen the day is driven on: the map on the left, the readings down the right, and along the bottom the chart and the detections.

MPB main screen — The main screen while driving.

The right-hand column, top to bottom

The top of the side bar — The lights, the buttons, the wind, the concentration, and the two actions that write into the session.

Block	What it is
D N F	The three lights of the previous section.
EXIT	Closes the application. It asks first, unless that question has been switched off in the logger settings.
REC	Starts and stops the recording of a session.
The arrow	Opens the export panel: KML, report, upload.
The gear	Opens the settings menu.
Load KML	Puts the customer's pipeline plan on the map.
WIND	The anemometer, if one is fitted: speed in m/s and the direction the wind is coming from. rel. means the angle is relative to the vehicle rather than to north.
The large number	The concentration now, in ppm, with the alarm threshold above it. The block turns red when the threshold is crossed.
QUANTIFY HERE	Measures the emission rate of a leak the vehicle is standing in. Section 10.
Base	Rewrites the instrument's zero on clean air. Section 6.
Add comment	Writes a note into the session at the current position. Section 7.

The readings

Field	What it is
Concentration	The same number as the large one above, in ppm.
Time	The time of the reading, to a tenth of a second. It comes from the satellite receiver, which is the clock everything else is stamped with.
Latitude, Longitude	Where that reading was taken. Blank or frozen means the N light is not green.
Flow	The flow through the cell, from the sensor board. The number behind the F light.
Air temp, Board temp	The two temperature probes: the air leaving the pump, and the board itself, which is the one that says whether the cabinet is overheating.
Temp 3	A third probe, not fitted on these instruments. It stays blank, and that is correct.

Note: Six dashes mean no reading. On an instrument without the flow board, Flow and the temperatures are dashes all day and nothing is wrong.

Under the map

Speed, signal, accuracy and the detections table — Above: how fast, how much light, how good the fix. Below: the detections of this session, newest on the left.

Field	What it is
Speed, km/h	From the satellite receiver, not from the vehicle. It is also what the quantification refuses to work above.
Signal, mV	The light reaching the detector, as on the startup screen. Watch it over weeks rather than minutes: a slow decline is dirty optics.
GPS accuracy, m	How well the position is known. A couple of metres is good; tens of metres, under trees or between tall buildings, means a detection cannot be placed precisely and is worth a comment.

The table underneath is the detections of this session, not the last few readings. A new column appears each time the concentration rises above the threshold, and while the gas lasts that column keeps the highest value reached and the position where it was reached. The newest is on the left. It is the running answer to "what have we actually found today", and it is the same list the KML and the report are built from.

The chart

The concentration chart — The scale buttons on the left, the traces in the middle, and the handle along the bottom that sets how much time is shown.

The chart draws the last stretch of time. Auto scales it to whatever is in the window, and x10, x50, x300 hold a fixed scale instead. Auto is the honest default, but with one strong peak in the window everything else is flattened against the axis — a fixed scale is what shows a small rise for what it is.

Changing the time shown

The pale handle along the bottom of the chart sets the window, and the figure beside it says what it is now: Period 120 sec. Drag it left for a longer window and right for a shorter one; the range is 30 seconds to 5 minutes.

Short, 30 to 60 seconds. For driving slowly along a suspect stretch: the shape of a single plume is visible as it passes.
Long, 3 to 5 minutes. For a normal round: it shows whether the baseline is steady, which is what tells you the instrument is behaving.

The same setting is under Data logging settings, as The period shown on the chart, for anyone who would rather type it than drag it. It changes only the drawing; everything is recorded whatever the chart is showing.

Note: Tapping the chart itself switches which traces are drawn. The default pair is not in ppm; the concentration in ppm is the large number in the column, and it is what the recording keeps.

6. Base: the instrument's zero

The instrument measures how much more methane is in the sampled air than in the air it was last told to call clean. That reference is the base, and pressing Base rewrites it: it takes the air being sampled at that moment and calls it zero.

It has to be rewritten from time to time because the instrument drifts — slowly, with temperature, over hours. Left alone too long the baseline creeps, and a creeping baseline either buries small leaks under it or invents them.

When to press it

When the software asks. The button draws attention to itself when the instrument judges that its zero is due. That is the normal case, and the interval is set under Autobasing interval.
At the start of the round, once the warm-up has finished and the vehicle is somewhere with ordinary air.
When the reading sits at a small non-zero value street after street with no gas anywhere. That is drift, not a city-wide leak.

Where not to press it

Careful: Never press Base in gas. Whatever the instrument is breathing at that instant becomes the new zero, so doing it over a leak teaches the instrument that the leak is normal air — and it will then read nothing there, and negative once it has driven away. If it happens, drive to clean air and press it again.

Clean air means away from the plume: not beside a gas cabinet, not behind a bus, not in a closed courtyard, not over the leak that has just been found. A hundred metres up the road is usually enough.

The padlock

The padlock beside the button locks it. It exists because this is a touch screen in a moving vehicle, and rewriting the zero by accident with a knee or a sleeve is a thing that happens. Tap the padlock to unlock, press Base, and it locks itself again.

7. Add comment

A comment is a note written into the session at the position the vehicle is at when it is confirmed. It is how the crew tells the office something the numbers cannot: what was there, what it looked like, why a reading is not what it seems.

The Add comment screen — Five ready-made notes for the things that recur, and a free text box for everything else.

The five buttons are the notes that come up on every survey. Press one and it fills the comment; press Confirm and it is written.

Button	When to use it
Underground leak	A detection judged to come from the buried main under the carriageway.
Crane node	A valve chamber. They leak at the stem and are worth marking whether or not there is a reading.
Gas distribution station	A pressure reduction or distribution station, where a background of gas is normal and should not be read as a fault.
Cabinet gas control room	A regulator cabinet at the roadside or on a wall.
Connection node	A service connection or a joint on the main.

The text box takes anything else, and this is where the day's real value is often written. Worth recording: roadworks over the pipe, a parked lorry that made the street impossible to cover, a smell with no reading, a stretch driven twice because of traffic, a manhole that had been left open.

Tip: Write the comment where it belongs, not at the end of the street. The note is filed at the position the vehicle is at when Confirm is pressed, and a note fifty metres past what it describes is a note somebody will misread in the office.

Note: Comments go into their own file in the session and appear in the exported document. They are never mixed into the measurements, so a comment can never change a reading.

8. Recording a session

Nothing is kept until recording starts. The instrument measures from the moment it is warm, and the map draws, but until REC is pressed none of it is written to disk.

A session is one continuous piece of recording. A day can hold as many as you like — one per street, one per district, or one for the whole morning — and they are numbered in order, 000, 001, and so on.

Before pressing REC

Fill in the day's details under Data logging settings: unit number, area, operators, weather, customer. They are written into the session at the moment it opens and cannot be added afterwards.
Check the lights: D green, N green, and F green if the board is fitted. A round recorded with N red has readings and no positions, which for a survey is the same as nothing.
Press Base in clean air, if it has not been done since the warm-up.
Load the pipeline plan, if the round needs it.

During the round

Press REC. The button shows that recording is running.
Drive the round at working speed. One pass along each street is the survey.
Use Add comment for anything the numbers will not remember.
Watch the detections table under the map: it is the running list of what has been found.
Press REC again at the end. The session is closed and written.

What gets written

Every session produces the same set of files: the measurements at full rate, an averaged series, the track, the detections, the comments, what the instrument reported about itself, and the wind if an anemometer is fitted. Section 13 lists them.

Careful: Close the session before switching the computer off. A session that was never stopped keeps its measurements, but not the closing line that carries the day's settings — and the report reads that line.

Tip: Stop and start a new session when something changes that the office should be able to separate: a different district, a different customer, after lunch. It costs one press and it makes the day easier to hand over.

9. The map and the pipeline plan

The map follows the vehicle and draws the track behind it. Detections are marked on the track as they happen, so the round that has been covered is visible at a glance — which is most of what the map is for.

Loading the network

Load KML puts the customer's pipeline plan on the map, from a .kml or .kmz file. The mains are then drawn under the track and it is possible to see, while driving, whether the street being covered is the one that was meant to be covered.

Tip: Load the plan before starting, not in the middle of a street. Reading a large file takes a few seconds, and those are seconds spent looking at the screen instead of at the road.

Note: The plan is only drawn. Nothing in the recording depends on it, and MPB never says that a leak belongs to a pipe on it.

10. Quantifying a leak

A concentration says there is gas. It does not say how much is coming out. QUANTIFY HERE turns the reading into an emission rate in grams per hour, by measuring the gas together with the wind that is carrying it away.

The vehicle has to be standing. A measurement taken while moving mixes the plume with the vehicle's own motion and the number that comes out is meaningless, so the button refuses above walking pace and abandons a measurement whose vehicle pulls away.

Stop the vehicle in the gas, with the intake where the reading was highest.
Press QUANTIFY HERE. The panel shows the seconds elapsed and the share of the sample collected.
Wait. The measurement runs for about a minute and a half; STOP abandons it.
The result appears as a rate in g/h with a band around it. QUANTIFY AGAIN repeats it.

The quantification tab — The Quantification tab of the export panel lists the rates measured during the day. With no wind recorded there is nothing to compute, and it says so.

Careful: Without a wind reading there is no rate. The wind speed is half of the calculation, and it is measured, not assumed — on an instrument with no anemometer the button has nothing to work with.

Reading the band

The band is not decoration. The depth of the layer of air the gas is leaving through cannot be measured from the vehicle, only assumed, and that assumption is the whole uncertainty: a factor of two or three either way. The rate is a size — grams an hour, not kilograms — and it should be quoted as one.

11. Exporting and uploading

The export panel opens from the arrow button beside REC. It does three separate things, and each of them can be run for the last session alone or for the whole day.

Export KML

Writes the recorded track, with the detections marked along it, as a file any map viewer opens — Google Earth among them. You choose where it goes, which in the field is usually a memory stick.

Export report

Builds the document the crew leaves behind: cover, summary, instrument, route on a map, and the detections with their severity. Before it is written a form asks for what the instrument cannot know — client, contractor, vehicle, and what the crew saw.

The result is a PDF. Where no browser can be found to print it, the HTML is left at the destination instead, with a message saying to print it by hand: the work is done either way.

Upload data

Sends the session files to the survey server, so the day is not left on one computer. Files already on the server with the same size are skipped, which makes a second upload of the same evening cost seconds; a session still being written grows, so it is sent again.

Tip: Upload at the end of every day, not at the end of the week. It is the only copy of the day that does not live in the vehicle.

12. Settings

The gear button opens the settings menu. Most of it is set up once when the instrument is installed and never touched again; the two an operator uses are the logger and, when a spare antenna goes on, the GPS.

Careful: The first four entries are the instrument's own settings. They decide how the measurement is made, and a wrong value there does not announce itself — the instrument goes on producing plausible numbers that are wrong. Do not change them without being asked to.

Data logging settings

The day's identity, and where the recordings are written. What is typed here goes into every session that follows, so it belongs at the start of the day rather than at the end.

Logger settings — System and unit number name the instrument; area, operators, weather and customer name the day.

Field	What it is
Log directory	Where the day's folders are created. An external drive is fine.
System, Unit Nr	Which instrument recorded the day. The system is fixed; the unit number is the one on the case, and it is worth getting right.
Area, Operators, Weather, Customer	Which day this is. These end up on the report.
Minimum time between leaks	Two rises closer together than this are treated as one detection. It stops a single plume being reported as a handful.
Changing the scale	The three fixed scales offered under the chart. Set a new value and press the button of the one to replace.
The period shown on the chart	The same window the handle under the chart sets, in seconds.
Map tile cache size	How much map to keep on disk. A larger cache means more of the round still draws where there is no signal.
Exit without operator's request	Closes without asking. Leave it off in a vehicle.

GPS settings

The position normally comes from the instrument itself. A USB antenna is carried as a spare so that a failed instrument antenna does not end the survey, and this is where it is switched on.

Leave the port on Automatic unless there is a reason: it finds the antenna by itself and tries the likely ports first. Name a port when several serial devices are fitted and the search should not go near them.

Note: The status lines under the form are the fastest way to tell a broken antenna from a missing fix. An open port with nothing arriving is the wrong port; a working receiver with no fix wants sky, and indoors it may never get one.

Sensor board settings

The board reports the flow as pulses per second, and what counts as healthy depends on the filter fitted. Read the value with a clean filter, then a half loaded one, then a spent one, and set the three thresholds between them: warning turns the F light yellow, alarm turns it red and asks for the filter, and no flow is the value at or below which nothing is flowing at all and the light goes grey.

Careful: The protocol version is a setting and is never guessed from the data. The two versions send the flow with the bytes the other way round, so the wrong version produces readings that look perfectly reasonable and are not. Leave Port speaks Telnet off unless the converter really negotiates: on a plain port it eats part of a temperature and no frame decodes.

Wind sensor settings

Nothing is ever written to the sensor's own configuration; it is polled once a second and that is all. If the port opens and nothing arrives, the baud rate or the listener identifier is wrong — the sensor ignores a message addressed to anybody else without complaining.

Cloud upload settings

The instrument name is the folder the days are filed under on the server, so several vehicles can share one. Press Test connection after any change: it says in one line whether the server answers, whether the password is accepted, and whether the folder can be written — which is worth knowing in the office rather than at the end of a survey.

Autobasing interval

Shorter means a steadier baseline and more interruptions; longer means fewer interruptions and more drift. It is the other half of section 6.

Operating mode

UDP over Ethernet is how these instruments are wired; the serial alternative is there for a bench. The two port numbers must match what the instrument expects, and there is no reason to change them in the field.

Localization options

Set the language, then Apply changes. Use a virtual keyboard should stay ticked on a touch screen with no keyboard attached, or the text fields cannot be filled in at all.

The instrument's own settings

These four are set at commissioning and are listed here only so that they can be recognised and left alone.

Entry	What it is
Calculation settings	How the instrument turns the absorption it sees into a concentration.
Operating parameters settings	The instrument's working parameters, and the Automatic temperature mode selection of section 3.
Laser settings	The laser's own coefficients. Changing one of these puts the instrument off the absorption line.
Test mode settings	Temperature and current setpoints, the regulator gains, and the thresholds for finding the line. A service screen.
Link settings	The instrument's own network identity: ports, MAC, IP, gateway. Section 2 depends on this being right.
Sensitivity options	The concentration threshold the screen and the detections table use.

Link settings, for reference. The Ethernet half is what section 2 relies on.

13. What a day leaves behind

Recordings are written under the folder chosen in the logger settings, one folder per day and one set of files per session:

Documents\MPB\2026-09-08\data\ Info_Acq.ses one line per session fast_080926_000.dat every measurement slow_080926_000.dat the averaged series track_080926_000.dat position and time detr_080926_000.dat the reference spectrum leak_080926_000.txt the detections note_080926_000.txt the comments error_080926_000.txt what the instrument reported wind_080926_000.txt the anemometer, if fitted

The number in the name counts the sessions of the day: 000 is the first, 001 the second. The date is in the name too, so files stay identifiable once they have been copied somewhere else.

Careful: Do not rename, edit or tidy these files. The processing software reads them by position, byte for byte; a file opened and saved by something else is a file that no longer reads. Copy them by all means — that is what the upload does.

14. If something does not respond

The search screen never ends

The instrument is not answering. Check that it is powered and that the Ethernet cable is in. If the line at the bottom of that screen says the network address is missing, the computer has lost the fixed address the instrument is reached at, and that has to be put back before anything else will work.

D is red

Same cause as above, only after the software has started: the instrument has stopped answering. Cable, power, then restart the software. Readings drawn while D is red are the last ones received and not new measurements.

N is red or yellow

Yellow means the receiver is alive and has no fix — wait, or move where there is sky. Red means no receiver at all: check the antenna and, if a USB antenna is being used, open the GPS settings, where the status lines say which of the two it is.

Without a position the concentrations are still measured and recorded, but there is nothing to say where they were measured, which for a survey is the same as not having them.

F is red, or the alarm asks for the filter

The flow through the cell has fallen below the alarm level, and the usual cause is a dirty filter. Change it. If the flow does not come back, look for a crushed or disconnected hose before suspecting the filter again.

The warm-up never finishes

If the first bar sticks or falls back, the instrument cannot hold the temperature it is aiming at because the surroundings are too warm. Move up a temperature mode — Summer, or Supersummer on a hot day — and press Repeat. If the second bar is the one that never fills, the laser is not finding the absorption line: press Repeat once, and if it happens again report it with the Signal value.

The reading sits above zero everywhere

That is the instrument's zero having drifted, not a leak under every street. Drive to ordinary air and press Base. If it comes back within the hour, shorten the autobasing interval.

The reading is negative

Base was pressed in gas: the instrument was taught that air with methane in it is zero, so clean air now reads below it. Drive to clean air and press Base again.

The map is grey

The map tiles come over the internet. Without a connection nothing arrives and the map stays empty; the survey is unaffected, since the recording does not need the map. Tiles already seen stay available.

Quantify here says the vehicle must stop

It is refusing on purpose: above walking pace the measurement cannot be made. Stop properly, with the engine idling if need be, and press it again. If it says to drive a little first, the software has not yet seen enough movement to know which way the vehicle is pointing.

The report came out as HTML instead of PDF

The document is printed by a browser, and none was found on the computer, or the one found failed. The HTML at the destination is the same document and can be opened and printed by hand.

The upload does nothing

The status line under the button says why. No server set, a wrong password and a server that cannot be reached all read differently there. Empty sessions are never sent, so a day with nothing recorded reports that there is nothing to send.

Tip: When reporting a fault, say what the three lights were showing and what the screen said, word for word. It is usually enough to tell a cable from a setting without anyone travelling.