Operating Manual

Inverted Magnetron Pirani Gauge
MPG400
MPG401

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1

Product Identification

In all communications with INFICON, please specify the information given on the
product nameplate. For convenient reference copy that information into the spaceprovided below:

ValidityThis document applies to products with part number:
MPG400 (FPM sealed)

MPG401 (all-metal)

351-010351-011351-012351-020351-021351-022(DN 25 ISO-KF)(DN 40 ISO-KF)(DN 40 CF-C)(DN 25 ISO-KF)(DN 40 ISO-KF)(DN 40 CF-C)

The part number (PN) can be taken from the product nameplate.
If not indicated otherwise in the legends, the illustrations in this document
correspond to the product with part number 351-010. They apply to the otherproducts by analogy.
We reserve the right to make technical changes without prior notice.
All dimensions in mm.

Intended Use

The Inverted Magnetron Pirani Gauges MPG400 und MPG401 has been designed
for vacuum measurement in the pressure range of 5×10-9 … 1000 mbar.
The Inverted Magnetron Pirani Gauges must not be used for measuring flammableor combustible gases which react in air.
The gauges can be used with an INFICON Controller of the VGC40x / VGC50x
series or with another evaluation unit.

Functional Principle

Over the whole measuring range, the measuring signal is output as a logarithm of
the pressure.
The gauge consists of two separate measuring systems (the Pirani and the cold
cathode system according to the inverted magnetron principle). They are combinedin such a way that for the user, they behave like one measuring system2

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Contents
Product Identification
Validity
Intended Use
Functional Principle

2
2
2
2

1 Safety
1.1 Symbols Used
1.2 Personnel Qualifications
1.3 General Safety Instructions
1.4 Liability and Warranty

4
4
4
4
5

2 Technical Data

6

3 Installation
3.1 Vacuum Connection
3.1.1 Removing the Magnet Unit (Only for Gauges With CF Flanges)
3.2 Electrical Connection
3.2.1 Use With an INFICON Controller
3.2.2 Use With Another Control Device

9
9
11
12
12
12

4 Operation
4.1 Measurement Principle, Measuring Behavior

13
13

5 Deinstallation

15

6 Maintenance
6.1 Adjusting the Gauge
6.2 Cleaning MPG400, Replacing Parts
6.2.1 Disassembling MPG400
6.2.2 Cleaning MPG400
6.2.3 Reassembling MPG400
6.3 Cleaning MPG401, Replacing Parts
6.3.1 Disassembling MPG401
6.3.2 Cleaning MPG401
6.3.3 Reassembling MPG401
6.4 Troubleshooting

16
16
18
18
19
20
21
22
23
24
25

7 Accessories

26

8 Spare Parts

26

9 Returning the Product

28

10

28

DisposalAppendix
A: Measuring Signal vs. Pressure
B: Gas Type Dependence

29
29
30

ETL Certification31

For cross-references within this document, the symbol (→  XY) is used.

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3

1 Safety
1.1 Symbols Used

DANGER
Information on preventing any kind of physical injury.

WARNING
Information on preventing extensive equipment and environmental damage.

CautionInformation on correct handling or use. Disregard can lead to malfunctions or
minor equipment damage.

1.2 Personnel Qualifications
Skilled personnel
All work described in this document may only be carried out by persons who
have suitable technical training and the necessary experience or who have been
instructed by the end-user of the product.

1.3 General Safety
Instructions•

Adhere to the applicable regulations and take the necessary precautions for theprocess media used.
Consider possible reactions between the materials (→  7) and the process
media.
Consider possible reactions (e.g. explosion) of the process media due to theheat generated by the product.

•

Adhere to the applicable regulations and take the necessary precautions for all
work you are going to do and consider the safety instructions in this document.

•

Before beginning to work, find out whether any vacuum components are contaminated. Adhere to the relevant regulations and take the necessary precautions when handling contaminated parts.

DANGERDANGER: magnetic fields
Strong magnetic fields can disturb electronic devices like heart
pacemakers or impair their function.
Maintain a safety distance of ≥10 cm between the magnet and theheart pacemaker or prevent the influence of strong magnetic fields byantimagnetic shielding.
Communicate the safety instructions to all other users.

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1.4 Liability and Warranty

INFICON assumes no liability and the warranty becomes null and void if the enduser or third parties•

disregard the information in this document•

use the product in a non-conforming manner•make any kind of interventions (modifications, alterations etc.) on the product•use the product with accessories not listed in the corresponding productdocumentation.

The end-user assumes the responsibility in conjunction with the process media
used.
Gauge failures due to contamination, as well as expendable parts (filament), arenot covered by the warranty.

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2 Technical Data
Measuring range (air, N2)
Accuracy (N2)5×10-9 … 1000 mbar≈±30%
in the range 1×10-8 … 100 mbar

Reproducibility≈±5%in the range 1×10-8 … 100 mbar

Gas type dependence→ Appendix B

Output signal (measuring signal)
Voltage range
Measuring range
Voltage vs. pressure
Error signal

0 … +10.5 V
1.82 … 8.6 V
logarithmic, 0.6 V / decade(→ Appendix )<0.5 V no supply>9.5 V Pirani measurement element
defective (filament rupture)

Output impedance

2×10 Ω

Minimum loaded impedance

10 kΩ, short-circuit proof

Response time (pressure dependent)
p > 10-6 mbar
p = 10-8 mbar

<10 ms≈1000 ms

Gauge identification

85 kΩ referenced to supply common

Status-2
p > 10 mbar
Pirani-only modep < 10-2 mbar
Cold cathode not ignited
Pirani-only modep < 10-2 mbar
Cold cathode ignited
Combined Pirani / cold cathode
mode
Lamp

Pin 6
Low = 0 V
Low = 0 V

High = 15 … 30 V (dc)High voltage on (LED on)

SupplyDANGER
The gauge may only be connected to power supplies, instruments orcontrol devices that conform to the requirements of a grounded extralow voltage (PELV). The connection to the gauge has to be fused1).
Supply voltage at the gauge
15.0 … 30.0 V (dc) (ripple ≤ 1 Vpp)
Power consumption
≤2 W
≤1 AT
Fuse1)The minimum voltage of the power supply must be increased proportionally to thelength of the sensor cable.
Voltage at the supply unit with
16.0 … 30.0 V (dc) (ripple ≤ 1 Vpp)maximum line length

1)

6

INFICON controllers fulfill these requirements.
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Adjustment<HV> potentiometer<ATM> potentiometer
Electrical connection
Sensor cableLine length

FCC68 female, 8 poles
8 conductors plus shielding

Operating voltage
Operating current≤3.3 kV≤500 µA

Grounding concept→ ("Electrical Connection")

Vacuum connection-signal common

connected via 10 kΩ
(max. voltage differential
with respect to safety±50 Vwith respect to accuracy ±10 V)
conducted separately

Supply common-signal common
Materials exposed to vacuum
Vacuum connection
Measuring chamber
FeedthroughInternal seals
MPG400
MPG401
Anode
Ignition aid
Pirani measuring tube
Pirani filament

stainless steel
stainless steel
ceramic
FPM 75
Ag, Cu, soft solder (Sn, Ag)Mo
stainless steel
Ni, AuW

Internal volume≈20 cm³≤10 bar (absolute)
limited to inert gases

Bakeout

Pirani filament
Storage
Relative humidity
Use
Degree of protection

MPG400-401.om(8×0.14 mm²)any

Temperatures
Operation
MPG400
MPG401(2017-10)≤50 m

Mounting orientation

Pressure

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at <10-4 mbar
at atmospheric pressure+5 … +55 °C+5 … +150 °C(at flange in horizontal mounting orientation, without magnetic shielding)+150 °C(without magnetic shielding andelectronics unit)+120 °C–40 °C … +65 °C≤80% at temperatures up to +31 °C
decreasing to 50% at +40 °C
indoors only
altitude up to 2000 m
IP 40

7

92

75

15.5

55

105

55

75

MPG40160

MPG40060

Dimensions [mm]

ø 63.5

18.5

32

24

18

28

ø 63.5

DN 25 ISO-KF

DN 40 ISO-KF

DN 40 CF-F

Weight351-010351-011351-0128≈700 g≈720 g≈980 g351-020351-021351-022≈730 g≈750 g≈1010 gtina48e1-c(2017-10)

MPG400-401.om

3 Installation
3.1 Vacuum Connection

DANGERDANGER: overpressure in the vacuum system >1 bar
Injury caused by released parts and harm caused by escaping processgases can result if clamps are opened while the vacuum system ispressurized.
Do not open any clamps while the vacuum system is pressurized. Use
the type of clamps which are suited to overpressure.

DANGERDANGER: overpressure in the vacuum system >2.5 bar
KF flange connections with elastomer seals (e.g. O-rings) cannot
withstand such pressures. Process media can thus leak and possibly
damage your health.
Use O-rings provided with an outer centering ring.

DANGERDANGER: protective ground
Products that are not professionally connected to ground can be
extremely hazardous in the event of a fault.
The gauge must be electrically connected to the grounded vacuum
chamber. The connection must conform to the requirements ofprotective connection according to EN 61010:•

CF connections fulfill this requirement.

•

For gauges with KF connections, use a conductive metallic clamping ring.

CautionCaution: vacuum component
Dirt and damages impair the function of the vacuum component.
When handling vacuum components, take appropriate measures toensure cleanliness and prevent damages.

CautionCaution: dirt sensitive area
Touching the product or parts thereof with bare hands increases thedesorption rate.
Always wear clean, lint-free gloves and use clean tools when working
in this area.

WARNINGWARNING: electric arcing
Helium may cause electric arcing with detrimental effects on theelectronics of the product.
Before performing any tightness tests put the product out of operation
and remove the electronics unit.

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9

The gauge may be mounted in any orientation. To keep condensatesand particles from getting into the measuring chamber preferablychoose a horizontal to upright position and possibly use a seal with acentering ring and filter.
If adjustment should be possible after the gauge has been installed, besure to install it so that the <HV> and <ATM> trimmer potentiometers
can be accessed with a screw driver (→  16).

Procedure

Remove the protective lid and install the product to the vacuum system.
When making a CF flange connection, it may be advantageous to temporarily
remove the magnet unit (→  11).

Seal with centering ringorProtective lid
Clamp

Seal with centeringring and filter

Keep the protective lid.

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3.1.1 Removing the Magnet
Unit (Only for Gauges
With CF Flanges)
Tools required•

Allen wrench 1.5 mm•

Open-end wrench 7 mm

Procedure

2
1
4
7

3

a) Unfasten the hexagon socket set screw (1) on the electronics unit (2).
b) Remove the electronics unit without twisting it.
c) Unfasten the hexagon head screw (3) on the magnet unit (4) and remove themagnet unit.
The magnetic force and the tendency to tilt make it difficult toseparate the magnet unit and the measuring chamber (7).
d) Make the flange connection between the gauge and the vacuum system.
e) Remount the magnet unit and lock it with the hexagon head screw (3).
f) Carefully mount the electronics unit (2). (Make sure the pin of the Pirani element is properly plugged into the corresponding hole of the electronics unit.)g) Push the electronics unit up to the mechanical stop and lock it with the hexagon
socket set screw (1).

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113.2 Electrical Connection
Precondition

Make sure the vacuum connection is properly made (→  9).

3.2.1 Use With an INFICON
Controller

Connect the sensor cable to the gauge and the controller.

3.2.2 Use With Another Control
Device Make a sensor cable according to the diagram.

Electrical connection
Pin 1
Supply (15 … 30 V (dc)
Pin 2
Supply common
Pin 3
Signal output (measuring signal)
Pin 4
Identification
Pin 5
Signal common
Pin 6
StatusPin 7, 8 n.c.
8-pin
FCC-68connector

 Connect the sensor cable to the gauge and the controller.

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4 Operation
As soon as the required supply voltage is applied, the measuring signal is available
between pins 3 and 5. (→ Appendix for the relationship between the measuring
signal and the pressure).
Allow for a stabilizing time of approx. 10 min. Once the gauge has been switchedon, permanently leave it on irrespective of the pressure.

4.1 Measurement Principle,
Measuring Behavior

The gauge consists of tow separate measuring systems (Pirani and cold cathodesystem according to the inverted magnetron principle). They are combined in sucha way that for the user, they behave like one measuring system.
The optimum measuring configuration for the particular pressure range, in whichmeasurement is performed, is used:1000 mbar

10-4 mbar

Cald cathode5×10-9 mbar

Pirani10-2 mbar•

The Pirani measuring circuit is always on•

The cold cathode measuring circuit is controlled by the Pirani circuit and isactivated only at pressures <1×10-2 mbar

The identification output (pin 6) indicates the current status of the gauge:
Pressure

Lamp on thegauge

p > 1×10-2 mbarp < 1×10-2 mbarp < 1×10-2 mbar

Operating mode

Pin 6

Pirani-only mode

Low = 0 V

Cold cathode not
Low = 0 V
ignitedPirani-only mode
Cold cathode ignited
High = 15 … 30 VDC
Combined Pirani / cold
cathode mode

As long as the cold cathode measuring circuit has not ignited, the measuring valueof the Pirani is output as measuring signal.

Gas type dependence

The measuring signal depends on the type of gas being measured. The curves areaccurate for dry air, O2, CO and N2. They can be mathematically converted forother gases (→ Appendix B).
If you are using an INFICON controller, you can enter a calibration factor to correct
the pressure reading (→  of that controller).

Ignition delay

An ignition delay occurs when cold cathode gauges are switched on. The delay
time increases at low pressures and for clean, degassed gauges it is typically:
10-5 mbar ≈1 second
10-7 mbar ≈20 seconds
5×10-9 mbar ≈2 minutes
The ignition is a statistical process. Already a small amount of depositions on the
inner surfaces can have a strong influence on it.

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13

As long as the cold cathode measuring circuit has not yet ignited, the measured
value of the Pirani is output as measuring signal. The identification output (pin 6,low) indicates the Pirani-only mode.

If the gauge is activated at a pressure p < 3×10-9, the gauge cannot
recognize whether the cold cathode system has ignited.

Once flanged on, permanently leave the gauge in the operating mode
irrespective of the pressure range. Like this, the ignition delay of the cold
cathode measuring circuit is always negligible (<1 s), and thermal
stabilizing effects are minimized.

Contamination

Gauge failures due to contamination, as well as expendable parts(filament), are not covered by the warranty.
Gauge contamination is influenced by the process media used as well as by any
present or new contaminants and their respective partial pressures. Continuous
operation in the range of 10-4 mbar … 10-2 mbar can cause severe contamination
as well as reduced up-time and maintenance cycles. With constantly low pressures(p <1×10-6 mbar), the gauge can be operated for more than one year withoutcleaning (cleaning the gauge →  18, 21).
Contamination of the gauge generally causes a deviation of the measured values:•

In the high pressure range (1×10-3 mbar … 0.1 mbar), the pressure reading is
too high (contamination of the Pirani element). Readjustment of the Pirani
measuring system →  16.

•

In the low pressure range (p < 1×10-3 mbar), the pressure reading is usually too
low (contamination of the cold cathode system). In case of severe contamination, instabilities can occur (layers of the measuring chamber peel off).
Contamination due to insulation layers can even lead to a complete failure of
the discharge ("Underrange" is displayed).

Contamination can to a certain extent be reduced by:•geometric protection measures (e.g. screenings, elbows) for particles thatspread rectilinearly•

mounting the flange of the gauge at a place where the partial pressure of thepollutants is particularly low.

Special precautions are required for vapors deposited under plasma (of the cold
cathode measuring system). It may even be necessary to temporarily switch of thegauge while such vapors occur.

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5 Deinstallation
DANGERDANGER: contaminated parts
Contaminated parts can be detrimental to health and environment.
Before beginning to work, find out whether any parts are contaminated. Adhere to the relevant regulations and take the necessary
precautions when handling contaminated parts.

CautionCaution: vacuum component
Dirt and damages impair the function of the vacuum component.
When handling vacuum components, take appropriate measures toensure cleanliness and prevent damages.

CautionCaution: dirt sensitive area
Touching the product or parts thereof with bare hands increases thedesorption rate.
Always wear clean, lint-free gloves and use clean tools when working
in this area.

Procedure Vent the vacuum system.
 Put the gauge out off operation and unplug the sensor cable.
 Remove the gauge from the vacuum system and install the protective lid.
When deinstalling the CF flange connection, it may be
advantageous to temporarily remove the magnet unit (→  11).

Protective lid

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15

6 Maintenance
Gauge failures due to contamination, as well as expendable parts(filament), are not covered by the warranty.

DANGERDANGER: contaminated parts
Contaminated parts can be detrimental to health and environment.
Before beginning to work, find out whether any parts are contaminated. Adhere to the relevant regulations and take the necessary
precautions when handling contaminated parts.

CautionCaution: vacuum component
Dirt and damages impair the function of the vacuum component.
When handling vacuum components, take appropriate measures toensure cleanliness and prevent damages.

CautionCaution: dirt sensitive area
Touching the product or parts thereof with bare hands increases thedesorption rate.
Always wear clean, lint-free gloves and use clean tools when working
in this area.

6.1 Adjusting the Gauge

Tools required

Procedure

The gauge is factory-calibrated. If used under different climatic conditions, throughextreme temperatures, aging or contamination, and after exchanging the sensor,
the characteristic curve can be offset and readjustment may become necessary
The cold cathode measuring circuit, which is dominant for low pressures(<1×10-3 mbar), is factory-calibrated and cannot be adjusted. By way of contrast,
the Pirani measuring circuit can be adjusted. Any adjustment has a negligible effecton the pressure range between approx. 10-2 mbar and 102 mbar.
•

Screw driver 1.5 mm•

Cylindrical pin ø≈3 mm

 If you are using a seal with centering ring and filter, check that they areclean or replace them if necessary (→  15).

 Put the gauge into operation (if possible, in the position, in which it will be
used later on).

 Evacuate the vacuum system to p << 10 mbar, and then wait 10 minutes.
-4 Turn the nameplate counter-clockwise until the mechanical stop is reached.
16

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MPG400-401.omWhile depressing the pin with the cylindrical pin, adjust the <HV>
potentiometer …
… to 4.20 Vor… to 5×10-4 mbar.

After that, turn the potentiometercounter-clockwise by 1/3 of a turn.

 Vent the gauge with air or nitrogen to atmospheric pressure, and wait atleast 10 minutes.

 Turn the nameplate clockwise until the mechanical stop is reached.
Using the 1.5 mm screwdriver, adjust the <ATM> potentiometer …
… to 8.60 Vor… to 1×103 mbar.

 Turn the nameplate back to its original position (it catches).

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17

6.2 Cleaning MPG400,
Replacing Parts

DANGERDANGER: cleaning agents
Cleaning agents can be detrimental to health and environment.
Adhere to the relevant regulations and take the necessary precautions
when handling cleaning agents and disposing of them. Consider
possible reactions with the product materials (→  7).

We recommend replacing the Pirani element when cleaning the gauge.

Tools / material required•

Allen wrench AF 1.5•

Allen wrench AF 3•

Open-end wrench 7 mm•

Pliers for circlip•

Polishing cloth (400 grain) or Scotch-Brite•

Tweezers•

Cleaning alcohol•

Mounting tool for ignition aid•

Ignition aid•

Pirani element (13) incl. FPM seal (13a)•FPM seal (11) for anode feedthrough6.2.1 Disassembling MPG400

2
1
7

4
3

6

8a

5

8

13
13a

9
10a
12

10

11

 Remove the gauge from the vacuum system (→  15).
 Unfasten the hexagon socket set screw (1) on the electronics unit (2).
 Remove the electronics unit without twisting it.
The cover of the electronics unit cannot be removed.

18

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 Unfasten the hexagon head screw (3) on the magnet unit (4) and remove
the magnet unit.
The magnetic force and the tendency to tilt make it difficult toseparate the magnet unit and the measuring chamber (7).

 Remove the circlip (5) and the polarity insert (6) from the measuring
chamber Remove the three hexagon socket screws (8) incl. lock washers (8a) on theback of the measuring chamber.

 Carefully remove the following parts in this order (without exerting stress on
the Pirani element (13)): pressure piece (9), complete anode (10), FPM seal(11) incl. support ring (12), Pirani element (13) incl. FPM seal (13a).
The parts can now be cleaned or replaced individually.

6.2.2 Cleaning MPG400
Cleaning the measuring
chamber and the polarity
insert Using a polishing cloth rub the inside walls of the measuring chamber andthe polarity insert to a bright finish.
The sealing surfaces must only be worked concentrically.

 Rinse the measuring chamber and the polarity insert with cleaning alcohol.
 Allow both to dry.
Cleaning or replacing theanode Remove the used ignition aid (10a) with tweezers.
 Using a polishing cloth rub the anode pin to a bright finish.
Do not bend the anode. Do not carry out mechanical work on theceramic part.

 Rinse the anode with cleaning alcohol.
 Allow the anode to dry.
 Insert a new ignition aid (10a) into the mounting tool.
 Carefully press the anode (clean or new)centered and parallel to the tool axis into
the ignition aid and insert it to a depth ofapprox. 15 mm. The final positioning isestablished after the anode is installed.

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Anode
Ignition aid
Mounting tool19

Cleaning the Pirani element Remove the FPM seal (13a) from the Pirani element (13).
 Fill the Pirani measuring tube with cleaning alcohol and let it work.
 Pour the alcohol out of the tube.
 Dry the tube (e.g. with a blow dryer <150 °C).
 Slide a new FPM seal over the Pirani element and insert it into the corresponding groove.

 Reinstall the Pirani element (→  20).
Replacing the Pirani element

If it is severely contaminated or defective.

 Slide a new FPM seal (13a) over the Pirani element (13) and insert it into
the corresponding groove.

 Mount the Pirani element (→  20).
6.2.3 Reassembling MPG400(→ figure  18)

 Insert the FPM seal (11) with the support ring (12) centered into themeasuring chamber (7). The sealing surface, seal, and ceramic part must
be clean.

 Carefully insert the anode (10) incl. ignition aid (10a) into the measuring
chamber.

 Insert the Pirani element (13) with the FPM seal (13a) slid over it into thecorresponding bore hole.

 Carefully place the pressure piece (9) on the measuring chamber andtighten them with the three hexagon socket screws (8) incl. lock washers(8a) uniformly until the stop position is reached.

 Position the ignition aid (10a) by pushing the mounting tool over the anodepin until the mechanical stop is reached.

 Blow the particles in the measuring chamber with dry nitrogen (be careful tohold the measuring chamber with the flange pointing downwards).

 Slide the polarity insert (6) into the measuring chamber until the mechanicalstop is reached.

 Place the circlip (5) snugly fitting on the polarity insert.
Visually check that the anode pin is centered over the middle
hole of the polarity insert (max. eccentricity = 0.5 mm).

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 If possible perform a leak test (leak rate <10 mbar l/s).
-9

WARNINGWARNING: electric arcing
Helium may cause electric arcing with detrimental effects on
the electronics of the product.
Before performing any tightness tests put the product out of
operation and remove the electronics unit.

 Mount the magnet unit (4) and lock it with the screw (3).
Carefully mount the electronics unit (2). (Make sure the pin of the Pirani element is properly plugged into the corresponding hole of the electronics unit.)
Push the electronics unit up to the mechanical stop and lock it with the
hexagon socket set screw (1).
Adjust the gauge (→  16).

6.3 Cleaning MPG401,
Replacing Parts

DANGERDANGER: cleaning agents
Cleaning agents can be detrimental to health and environment.
Adhere to the relevant regulations and take the necessary precautions
when handling cleaning agents and disposing of them. Consider
possible reactions with the product materials (→  7).

For cleaning the measuring chamber, the Pirani element must be
removed and replaced.

Tools / material required

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Allen wrench AF 1.5•

Allen wrench AF 3•

Open-end wrench AF 6•

Open-end wrench AF 7•

Pliers for circlip•

Polishing cloth (400 grain) or Scotch-Brite•

Tweezers•

Cleaning alcohol•

Mounting tool for ignition aid•

Ignition aid•

Metal seal (11) for anode feedthrough•

Pirani element (13) incl. set of seals (13a, 13b)21

6.3.1 Disassembling MPG401
13
13a
13b

2
1
9b
7

4

8a

3

8

9c

6
5

9
9a
10a
12

10

11

 Remove the gauge from the vacuum system (→  15).
 Unfasten the hexagon socket set screw (1) on the electronics unit (2).
 Remove the electronics unit without twisting it.
The cover of the electronics unit cannot be removed.

 Unfasten the hexagon head screw (3) on the magnet unit (4) and remove
the magnet unit.
The magnetic force and the tendency to tilt make it more difficult
to separate the magnet unit and the measuring chamber (7).

 Remove the circlip (5) and the polarity insert (6) from the measuring
chamber.

 Unfasten the hexagon socket set screw (9c) and remove the insulator (9b)without twisting it.

 Remove the four hexagon socket screws (8) incl. lock washers (8a) on theback of the measuring chamber.

 Carefully remove the following parts in this order (without exerting stress on
the Pirani element (13)): pressure piece (9), anode extension piece (9a),complete anode (10), metal seal (11) incl. centering ring (12).

 Unfasten the screw fitting (13a) of the Pirani element and remove Pirani element together with the copper seal (13b).
The parts can now be cleaned or replaced individually.

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6.3.2 Cleaning MPG401
Cleaning the measuring
chamber and the polarity
insert Using a polishing cloth rub the inside walls of the measuring chamber andthe polarity insert to a bright finish.
The sealing surfaces must only be worked concentrically.

 Rinse the measuring chamber and the polarity insert with cleaning alcohol.
 Allow both to dry.
Cleaning or replacing theanode Remove the used ignition aid (10a) with pliers.
 Using a polishing cloth rub the anode pin to a bright finish.
Do not bend the anode. Do not carry out mechanical work on theceramic part.

 Rinse the anode with cleaning alcohol.
 Allow the anode to dry.
 Insert a new ignition aid (10a) into the mounting tool.
 Carefully press the anode (clean or new)centered and parallel to the tool axis into
the ignition aid and insert it to a depth ofapprox. 15 mm. The final positioning isestablished after the anode is installed.

Replacing the Pirani element

Anode
Ignition aid
Mounting tool

 Slide the screw fitting (13a) and the copper seal (13b) over the Pirani
element (13).

 Mount the Pirani element (→  24).

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23

6.3.3 Reassembling MPG401(→ figure  22)

 Insert the Pirani element (13) with the screw fitting (13a) and copper seal(13b) slid over it into the corresponding conic bore hole (7) of the measuring
chamber.

 Tighten the screw fitting (13a) with your fingers while slightly pushing the
Pirani element against the mechanical stop. Then tighten the screw fitting
by one turn with the open-end wrench.

 Insert a new metal seal (11) incl. the centering ring (12) centered into themeasuring chamber (7).

 Carefully insert the anode (10) with the ignition aid (10a) and extension
piece (9a) slid onto it into the measuring chamber.

 Carefully place the pressure piece (9) on the measuring chamber.
 Insert the four hexagon socket screws (8) incl. lock washers (8a) andtighten them uniformly until the mechanical stop is reached.

 Carefully slide the insulator (9b) onto the pressure piece (9) and lock it withthe hexagon socket set screw (9c).

 Position the ignition aid (10a) by pushing the mounting tool over the anodepin until the mechanical stop is reached.

 Blow the particles in the measuring chamber with dry nitrogen (be careful tohold the measuring chamber with the flange pointing downwards).

 Slide the polarity insert (6) into the measuring chamber until the mechanicalstop is reached.
Place the circlip (5) snugly fitting on the polarity insert.
Visually check that the anode pin is centered over the middle
hole of the polarity insert (max. eccentricity = 0.5 mm).
If possible perform a leak test (leak rate <10-9 mbar l/s). If necessary slightly
retighten the screw fitting (13a).

WARNINGWARNING: electric arcing
Helium may cause electric arcing with detrimental effects on
the electronics of the product.
Before performing any tightness tests put the product out of
operation and remove the electronics unit.
Mount the magnet unit (4) and lock it with the hexagon head screw (3).
Carefully mount the electronics unit (2). (Make sure the pin of the Pirani element is properly plugged into the corresponding hole of the electronics unit.)
Push the electronics unit up to the mechanical stop and lock it with the
hexagon socket set screw (1).
Adjust the gauge (→  16).

24

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6.4 Troubleshooting

ProblemPossible cause

RemedyMeasuring signal
continually < 0.5 V"Error low".

No supply voltage.

Turn on the power
supply.

Measuring signal
continually > 9.5 V"Error high".

Pirani measurement
element defective(filament rupture).

Replace the Pirani
element(MPG400 →  20)(MPG401 →  23).

Electronics unit not correctly mounted.

Mount the electronics
unit correctly(MPG400 →  20)(MPG401 →  24).

The cold cathode discharge has not ignited.

Wait until the gas discharge ignites (in case ofcontamination with insulation layers, the cold
cathode may completely
fail to ignite).
(Cleaning
MPG400 →  18
MPG401 →  21).

The MPG has only been
activated withp < 3×10—9 mbar.

Slightly increase thepressure.

Pirani measurement circuit not adjusted, e.g.
due to severe contamination.

Readjust the Pirani
measurement circuit(→  16). If adjustment
is impossible, replace thePirani element.

Measurement of heavygases.

Convert with the corresponding formula(→  30).

The green lamp is ON and
the identification indicates
Pirani-only mode (measuring signal continually> 4.0 V).

Measuring signal continually > 5 V or display> 10-3 mbar althoughvacuum pressure is OK.

Severe outgassing in the Clean the measuringcold cathode measuring chamber.
chamber.
Measuring signal unstable.

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Gauge contaminated.

Clean the gauge(MPG400 →  18)(MPG401 →  21).

25

7 Accessories
When ordering accessories, always mention:•

all information on the product nameplate•description and ordering number according to the accessories list

Description
Magnetic shielding

Ordering number
BG443155-X

8 Spare Parts
When ordering spare parts, always mention:

MPG400•

all information on the product nameplate•description and ordering number according to the spare parts list

Pos.

Description
Maintenance kit, consisting of:
1× support ring
1× O-ring FPM ø3.69×1.78
1× O-ring FPM ø10.82× 1.78
3× ignition aid

351-999

12
13a
11
10a

Repair kit, consisting of:
1× Pirani element
1× support ring
1× O-ring FPM ø3.69×1.78
1× O-ring FPM ø10.82×1.78
3× ignition aid
1× anode, complete

351-998

13
12
13a
11
10a
10

Set of ignition aids, comprising:
10× ignition aid

351-995

10a

Mounting tool for ignition aid

351-994

13
13a

10

Ordering number

10a
12

11

Measuring system
DN 25 ISO-KF flange
DN 40 ISO-KF flange
DN 40 CF-F flange

26

BN846469-TBN846470-T
BN846471-T

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MPG401

Pos.

Description

Ordering number

Maintenance set, consisting of:
1× sealHNV 100 (9×1.6)
1× centering ring
3× ignition aid
1× washer (not used with MPG401)

351-99711
12
10aRepair set, consisting of:
1× Pirani element with glass feedthrough1× screw fitting
1× copper seal
1× anode extension piece
1× anode, complete
3× ignition aid
1× sealHNV 100 (9×1.6)
1× centering ring351-996

13
13a
13b
9a
10
10a
11
12

10a

Set of ignition aids, consisting of:
10× ignition aid

351-995

Mounting tool for ignition aid

351-994

13
13a
13b

9a
10
10a
12

11

Measurement system, complete
DN 25 ISO-KF flange
DN 40 ISO-KF flange
DN 40 CF-F flange

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BN846472-T
BN846473-TBN846474-T27

9 Returning the Product
WARNINGWARNING: forwarding contaminated productsContaminated products (e.g. radioactive, toxic, caustic or biologicalhazard) can be detrimental to health and environment.
Products returned to INFICON should preferably be free of harmful
substances. Adhere to the forwarding regulations of all involved
countries and forwarding companies and enclose a duly completed
declaration of contamination (form under www.inficon.com).
Products that are not clearly declared as "free of harmful substances" are decontaminated at the expense of the customer.
Products not accompanied by a duly completed declaration of contamination are
returned to the sender at his own expense.

10 Disposal
DANGERDANGER: contaminated parts
Contaminated parts can be detrimental to health and environment.
Before beginning to work, find out whether any parts are contaminated. Adhere to the relevant regulations and take the necessary
precautions when handling contaminated parts.

WARNINGWARNING: substances detrimental to the environment
Products or parts thereof (mechanical and electric components,
operating fluids etc.) can be detrimental to the environment.
Dispose of such substances in accordance with the relevant local
regulations.

Separating the components

28

After disassembling the product, separate its components according to thefollowing criteria:

Contaminated components

Contaminated components (radioactive, toxic, caustic or biological hazard etc.)
must be decontaminated in accordance with the relevant national regulations,separated according to their materials, and disposed of.

Other components

Such components must be separated according to their materials and recycled.

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Appendix
A:

Measuring Signal vs.
Pressure
Conversion formulae

p = 101.667U-d

⇔

p

U

c

d

[mbar][Torr]
[Pa]

[V]
[V]
[V]

6.8
6.875
5.6

11.33
11.46
9.333

where

Conversion curvesppressure
U measuring signal
c, d constant (pressure
unit dependent

U = c + 0.6log10 p

valid in the range-9

5×10 mbar < p <1000 mbar
-9
3.8×10 Torr < p <750 Torr
-75
5×10 Pa < p <1×10 Pa

Pressure p
Pa

1E+04

mbar
torr

1E+02

sensor error

overrange

underrange

1E–02

sensor error

1E+00

1E–04

1E–06

1E–08
0.0 0.5

1.5

2.5

3.5

4.5

5.5

6.5

7.5

9.5

8.5

10.5

Measuring signal U [V]

Conversion table

Meas. signal U [V]<0.5
0.5 … 1.82
1.82
2.0
2.6
3.2
3.8
4.4
5.0
5.6
6.2
6.8
7.4
8.0
8.6
8.6 … 9.5
9.5 … 10.5

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Pressure p [mbar]

Pressure p [Torr]

Pressure p [Pa]Sensor error
Underrange-9
5.0×10
3.8×10-9-8
1.0×10
7.5×10-9-7
1.0×10
7.5×10-8
1.0×10-6
7.5×10-7-5
1.0×10
7.5×10-6-4
1.0×10
7.5×10-5-3
1.0×10
7.5×10-4-2
1.0×10
7.5×10-3
7.5×10-4
0.1
1.0
0.75
10
7.5
100
75
1000
750
Overrange
Sensor error (Pirani defective)

5.0×10-7
1.0×10-6
1.0×10-5
1.0×10-4
1.0×10-3
1.0×10-2
0.1
1.0
10
100
1000
1.0×104
1.0×105

29

B:

Gas Type Dependence
Indication range above
10-2 mbar

Pressure indicated (gauge calibrated for air).
p (mbar)
102

H2 He

8

6
4

Ne
Air
N2
O2
CO

2

CO2
Ar

Indication range
above 10-2 mbar

101
8
6
4

Freon 12
Kr

2

Xe

100
8
6
4
2

10–1
8
6
4
2

Water vapor

10–2
10–3 2

Indication range
10-6 … 0.1 mbar

4 6 810–2 2

4 6 810–1 2

4 6 8 100

2

4 6 8 101

2

4 6 8 102

peff (mbar)

Pressure indicated (gauge calibrated for air).
p (mbar)
10–1
8
6
4
2

Indication range
10-6 ... 10-1 mbar

10–2
8
6
4
2

Ar

10–3
8
6
4
2

10–4

Air
N2
O2
CO

8
6
4
2

He

10–5
8

6
4
2

10–6
10–6 230

4 6 810–5 2

4 6 810–4 2

4 6 810–3 2

4 6 810–2 2

4 6 810–1

peff (mbar)

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Indication range below
10-5 mbar

In the range below 10-5 mbar, the pressure indication is linear. For gases otherthan air, the pressure can be determined by means of a simple conversion formula:peff = K × pressure indicatedwhere

gas typeK

air (O2, CO, N2)
Xe
Kr
Ar
H2
Ne
He

1.0
0.4
0.5
0.8
2.4
4.1
5.9

These conversion factors are average values.

A mixture of gases and vapors is often involved. In this case,accurate determination is only possible with a partial pressure
measurement instrument, e.g. a quadrupole mass spectrometer.

ETL Certification
RECOGNIZEDCOMPONENTETL LISTED
The products MPG400 and MPG401•

conform to the UL Standard UL 61010-1•

are certified to the CAN/CSA Standard C22.2 No. 61010-1

3103457

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31Original: German tina48d1-c (2017-10)

t i na48e1- c

LI–9496 Balzers
LiechtensteinTel +423 / 388 3111
Fax +423 / 388 3700
reachus@inficon.com
www.inficon.com