Witt MG 50-2ME Bedienungsanleitung

Instruction Manual for

WITT Gas Mixer

MG 50,100,200-2ME

MG 50,100,200-2ME PvDu

MG 50,100,200-2ME GB

Issue: 29.04.2016

This issue is not subject to change management

Page 2 of 27

WITT-GASETECHNIK GmbH & Co KG

Salinger Feld 4-8



: +49 (0)2302 89010

www.wittgas.com

Gas Safety- & Control Equipment

D-58454 Witten

Fax: +49 (0)2302 89013

witt@wittgas.com

1 Table of contents

1Table of contents......................................................................................................... 2

2Notes on this manual.................................................................................................. 4

2.1 What does this manual contain?.........................................................................................................4

2.2 Structure of the manual.......................................................................................................................4

2.3 Rights to this manual...........................................................................................................................5

2.4 What symbols are used?.....................................................................................................................5

2.5 Terms (in alphabetical order) ..............................................................................................................6

3Safety instructions and precautionary measures .................................................... 8

3.1 General safety instructions..................................................................................................................8

3.2 Gas mixer with oxygen........................................................................................................................9

3.3 Liability.................................................................................................................................................9

4Description ................................................................................................................ 10

4.1 Types ................................................................................................................................................10

4.2 Applications for the gas mixer...........................................................................................................11

4.3 Functional description of the gas mixer.............................................................................................11

4.3.1 Technical data on the gas mixer............................................................................................11

4.4 Function of the alarm module............................................................................................................12

4.4.1 Technical data on the alarm module......................................................................................12

4.4.2 The terminal strip (rear)..........................................................................................................12

5Setting up and installation ....................................................................................... 13

5.1 Checking for transport damage.........................................................................................................13

5.2 Place for setting up............................................................................................................................13

5.3 Safety instructions for installation......................................................................................................13

5.4 Installation of the pipes......................................................................................................................14

5.5 Electrical installation..........................................................................................................................15

5.5.1 Connection of the floating contacts........................................................................................15

6Commissioning and operation................................................................................. 16

6.1 Safety instructions for commissioning and operation........................................................................16

6.2 Commissioning the gas mixer...........................................................................................................16

6.3 Operating the gas mixer....................................................................................................................17

6.3.1 Setting the mixing valve (24) on models MG200...................................................................17

6.4 The alarm module..............................................................................................................................18

6.4.1 Buttons and displays..............................................................................................................18

6.4.2 Inlet pressure monitoring alarm..............................................................................................18

6.5 Malfunctions and rectification............................................................................................................19

6.5.1 Malfunction table....................................................................................................................19

6.6 Taking out of operation......................................................................................................................21

6.7 Short interruption in work ..................................................................................................................21

7Servicing and maintenance...................................................................................... 22

7.1 Safety instructions for servicing and maintenance............................................................................22

7.2 Repair instructions.............................................................................................................................22

7.3 Checks and servicing tasks...............................................................................................................23

7.4 Checking inlet filters for blockages....................................................................................................24

7.4.1 Plug filters (for version MG 50, MG 100, MG 200).................................................................24

7.4.2 Screwed filters (for version MG 200, MG 500).......................................................................24

7.5 Functional check on the electrical equipment...................................................................................24

7.6 Setting the receiver pressure ............................................................................................................24

7.7 Reset of the temperature monitor for the mixed gas temperature (optional) .........................................25

Page 3 of 27

WITT-GASETECHNIK GmbH & Co KG

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

: +49 (0)2302 89010

www.wittgas.com

Gas Safety- & Control Equipment

D-58454 Witten

Fax: +49 (0)2302 89013

witt@wittgas.com

8Concise instructions on operation ..........................................................................26

8.1 Switching on.......................................................................................................................................26

8.2 Switching off.......................................................................................................................................26

9Appendices................................................................................................................27

Page 4 of 27

WITT-GASETECHNIK GmbH & Co KG

Salinger Feld 4-8



: +49 (0)2302 89010

www.wittgas.com

Gas Safety- & Control Equipment

D-58454 Witten

Fax: +49 (0)2302 89013

witt@wittgas.com

2 Notes on this manual

You have decided for a gas mixer from WITT-GASETECHNIK.

With this manual, we would like to provide you with all the information necessary for safe, correct

setting up and installation, commissioning, operation and checking of the gas mixing system.

2.1 What does this manual contain?

The operation and maintenance of the WITT gas mixer are described in this manual.

Observance of the manual helps avoid hazards, down times due to incorrect operation and to en-

sure long service and reliability of the gas mixer.

The handling of gases, particularly inflammable and/or toxic gases, requires a high degree of cau-

tion. To prevent incorrect operation this instruction manual must be fully read carefully, and under-

stood, prior to the installation and commissioning of the gas mixer. This manual must be available

to the operating personnel during the operation of the gas mixer. The operating personnel must be

familiar with the operation of the gas mixer and instructed by qualified personnel.

If unexpected malfunctions occur that you cannot rectify with the assistance of the instruction man-

ual, please contact us stating the device number on the rating plate (see also technical data, Sec-

tion 9) or fax us the first page of the technical data with a short description of the fault. Do not for-

get to state your company, your name, and your telephone number.

Our address is:

WITT-GASETECHNIK GmbH & Co KG

Salinger Feld 4-8

D-58454 Witten

Tel.: +49 (0)2302 89010

Fax: +49 (0)2302 89013

You can of course also send us an e-mail (servi[email protected]) or visit our homepage at

http://www.wittgas.com.

In the case of modification to the gas mixing system this instruction manual ceases to be applica-

ble!

2.2 Structure of the manual

This manual is sub-divided into several sections:

In the “Notes on this manual” section the layout of the instruction manual is explained and

the terms and symbols used explained.

In the “Safety instructions and precautionary measures” section suggestions for safe us-

age of the gas mixer are listed. You should pay particular attention to this section as failure to

observe the information given here can result in equipment damage and physical injury.

In the “Description” section the function of the WITT gas mixer is explained based on the

function scheme.

The function of the integrated alarm module is addressed in the “Function of the alarm module”

section.

In the “Set up and installation” section you will find information on the correct location for set-

ting up the gas mixer and notes on both the gas and electrical installation.

In the “Commissioning and operation” section you will learn how you must proceed so that

mixed gas is produced and how you can change the composition of the mixed gas. Here you

will also find information on how to proceed if the alarm module signals insufficient inlet pres-

sure and the possible causes of this situation. You will also learn here how you can take the

gas mixer out or operation. e.g., for servicing tasks.

Page 5 of 27

WITT-GASETECHNIK GmbH & Co KG

Salinger Feld 4-8



: +49 (0)2302 89010

www.wittgas.com

Gas Safety- & Control Equipment

D-58454 Witten

Fax: +49 (0)2302 89013

witt@wittgas.com

Information on servicing tasks that you can perform yourself is given in the “Servicing and

maintenance“ section. Here you will also find notes on what you should check if, at some

point, a feature does not function correctly.

The “Concise operating instructions” provide you with information on the operation of the

gas mixer in short steps.

As an appendix to this manual you will find the technical data on the WITT gas mixer, the

schemes given in the technical data, along with drawings and a list of symbols. This provides a

short overview on the function and the controls on the gas mixer. You will also find the num-

bers for the symbols on the function scheme on the components themselves. With the aid of

the list of symbols and function scheme, you can identify components in the gas mixer.

2.3 Rights to this manual

This manual is the copyright of WITT-GASETECHNIK GmbH & Co KG.

Without the prior written agreement of WITT-GASETECHNIK GmbH & Co KG the manual is not

permitted to be duplicated or used in a manner contrary to the company’s due interests.

It is only permitted to pass this manual on to third parties in conjunction with the provision of the gas

mixer.

2.4 What symbols are used?

The attention symbol indicates hazards for man or the system.

It is imperative that these instructions are observed and followed.

The word “Caution!” is placed in front of information indicating risk of injury- and potentially

fatal hazards.

The word “Attention!”is placed in front of hazards for the system.

Note!

The pointing hand marks general notes that explain operating procedures.

The “dot” marks actions to be performed.

This symbol is used for a list.

This symbol indicates that you should turn the page.

This symbol indicates sections that only apply to the PvDu and GB versions.

PvDu

Page 6 of 27

WITT-GASETECHNIK GmbH & Co KG

Salinger Feld 4-8



: +49 (0)2302 89010

www.wittgas.com

Gas Safety- & Control Equipment

D-58454 Witten

Fax: +49 (0)2302 89013

witt@wittgas.com

2.5 Terms (in alphabetical order)

In this section the terms necessary to understand this manual are explained.

*These terms are explained in more detail in the following text.

Alarm module :

The alarm module is on the separate control housing. It signals insuf-

ficient gas inlet pressure* and indicates the corresponding gas.

Constant pressure (Pm) :

The individual gases are reduced to the constant pressure by the

constant pressure regulator unit*. The constant pressure is the pres-

sure of the individual gases from the dome or double dome loaded

pressure regulators.

Constant pressure

regulator unit :

The constant pressure regulator unit comprises dome or double dome

loaded pressure regulators and a p

ilot pressure regulator*. The gases

to be mixed are regulated to the required constant pressure* by the

constant pressure regulator unit.

Dome loaded pressure

regulator :

A dome loaded pressure regulator functions similarly to a spring-

loaded pressure reg

ulator, however in this case the force from the

spring is replaced by the pilot gas pressure on a membrane. If several

dome loaded pressure regulators are subjected to the same pressure-

regulated pilot gas, then the same constant pressure* is established a

each of the dome loaded pressure regulators.

Double dome loaded

pressure regulator :

A double dome loaded pressure regulator* can be considered as two

single dome loaded pressure regulators*. Both chambers in the dome

loaded pressure regulator are subje

cted here to a gas, the pilot gas*;

this results in exactly the same pressures being established at the

outlets of the dome loaded pressure regulator. Together with the pilot

pressure regulator*, the dome and double dome loaded pressure

regulators in a gas mixer form the constant pressure regulator unit*.

Gas inlet pressure (Pv) :

The pressure provided by the supplies for the individual gases is

termed the gas inlet pressure. A differentiation is made between static

and dynamic pressure. If no mixed gas is

produced, no gas flows. The

pressures now present at the inlet to the gas mixer are static pres-

sures. However, if mixed gas is produced, the gas inlet pressure

drops to the dynamic pressure as a function of the sizing of the gas

supply.

The static pressu

re is always higher that the dynamic pressure. The

static pressure (without mixed gas production) must not exceed the

maximum permitted inlet pressure. The dynamic pressure (during the

production of mixed gas) must not drop below the minimum required

gas inlet pressure (in the case that inlet pressure monitoring is acti-

vated, this would result in the triggering of the alarm).

Inlet pressure

monitoring :

The inlet gas pressure monitoring comprises pressure switches*

pressure transmitter* and an alarm mo

dule*. It is used to check for the

minimum gas inlet pressure required. The inlet pressure is only moni-

tored to check if the inlet pressure drops below the min. inlet pressure

given in the technical data.

Mixed gas output (QM) :

The mixed gas output is t

he mixed gas flow that the gas mixer can

produce in the normal operating state (P=1

bar; T=15 °C). The mixed

gas output will depend on the mixture this value relates to air.

Page 7 of 27

WITT-GASETECHNIK GmbH & Co KG

Salinger Feld 4-8



: +49 (0)2302 89010

www.wittgas.com

Gas Safety- & Control Equipment

D-58454 Witten

Fax: +49 (0)2302 89013

witt@wittgas.com

Mixing valve :

Mixing valves are only used in gas mixers for more than two gases.

The percentage portion of the related gas type is set on the mixing

valves. It must be noted that the total of all portions set must always

add up to 100%.

Non-return valve :

The non-

return valves prevent the gases from each individual phase

flowing back into the other gases.

Outlet pressure (Ph) :

The outlet pressure is the mixed gas pressure in the mixed gas re-

ceiver on the outlet of the gas mixer.

Pilot gas :

One of the gases used in the mixing process is defined as the pilot

gas and is used as the m

edium to be applied to the dome loaded

pressure regulators (via the pilot pressure regulator). If the supply of

the pilot gas is lost, the production of gas mixture is also lost com-

pletely. The pilot gas must therefore always be connected with suffi-

cient g

as inlet pressure, even if it is not used in the mixing process

itself.

Pilot pressure regulator :

The pressure to be applied to the dome loaded pressure regulator* is

adjusted on the pilot pressure regulator. In the dynamic condition, the

pilot pressure is slightly higher than the constant pressure.

Pressure switch /

Pressure transmitter :

The pressure switches or pressure transmitter

monitor the required

gas inlet pressures for the gases supplied. Together with the alarm

module, this then forms the inl

et pressure monitoring*. The pressure

switches only monitor the minimum inlet pressure required, and not

the maximum inlet pressure.

Proportional mixing

valve :

A proportional mixing valve is only found on gas mixers for two gases.

Here the percentage po

rtion of the gas named on the adjusting knob

is set. If the portion of a gas is increased, then portion of the other gas

is automatically reduced.

Receiver pressure (Pb) :

The receiver pressure is the pressure of the mixed gas in the mixed

gas receiver. It fluctuates between the minimum and maximum re-

ceiver pressure that is set on the pressure switch.

Supply gas :

All gases that are mixed including the pilot gas are termed supply

gases.

Page 8 of 27

WITT-GASETECHNIK GmbH & Co KG

Salinger Feld 4-8



: +49 (0)2302 89010

www.wittgas.com

Gas Safety- & Control Equipment

D-58454 Witten

Fax: +49 (0)2302 89013

witt@wittgas.com

3 Safety instructions and precautionary measures

It is imperative that the following safety instructions and precautionary measures are observed and

followed. They are intended to avoid hazards that can arise during the use of the system.

In addition, the applicable national health and safety regulations and safety regulations from the

trade associations are to be observed. For example, in Germany:

Health and safety regulations from the trade associations

a) DGUV Regulation 1 Grundsätze der Prävention (principles of prevention)

b) DGUV Regulation 3 Elektrische Anlagen und Betriebsmittel

(Electrical Systems and Equipment)

c) BGR 500 Sec. 2.33 Gase (Gases)

d) BGR 500 Sec. 2.32 Sauerstoff (Oxygen) - if used as a supply gas

The Pressure Devices Regulations and appropriate technical regulations

a) TRB 600 Aufstellung der Druckbehältern (Installation of Pressurised Vessels)

b) TRB 404 Ausrüstung der Druckbehälter, Ausrüstungsteile

Equipment for Pressurised Vessels, Equipment Parts)

c) TRB 700 Betrieb von Druckbehältern (Operating Pressurised Vessels)

must be observed.

No claim is made that this list is absolute.

Along with the instruction manual and the health and safety regulations applicable in the country

and place of use, recognised engineering regulations for safe and correct working are to be ob-

served.

The operating organisation must ensure that only authorised persons work on or with the system.

The gas mixer is built to the state of the art and is safe to operate. Hazards can be produced by the

gas mixer if it is used incorrectly by untrained personnel, or is not used for the purpose intended.

3.1 General safety instructions

Caution!

Only persons who have been instructed on the operation of the system and who have read

and understood this manual are permitted to use the system.

Observe national technical regulations on the handling of gases, e.g. applicable health and

safety regulations.

Any unauthorised modifications or changes to the system are forbidden for safety reasons.

Malfunctions arising during operation may only be rectified by trained personnel.

Maintenance- and repair tasks may only be performed by trained personnel.

During all maintenance- and repair tasks ensure that the gas mixer is isolated from mains elec-

tricity (also observe external voltage, e.g. via floating contacts) and is de-pressurised.

All supply pipes to and from the gas mixer are to be designed for the maximum permitted gas

pressure. If this is not possible for the system following the gas mixer, then it must be ensured

that the maximum permitted pressure for the following system cannot be exceeded by means

of the installation of suitable fittings, e.g., bursting discs or safety valves.

The material for the gas pipes (pipes from the gas supply to the inlets on the gas mixer), all fit-

tings installed there (e.g. shut-off valves, gauges, etc.) and all sealing elements there must be

designed for the related type of gas.

The material for the gas outlet pipe (pipe from the outlet on the gas mixer to the load), all fit-

tings installed there (e.g. shut-off valves, gauges, etc.) and all sealing elements there must be

designed for all the related types of gas.

The maximum gas inlet pressures in the technical data must not be exceeded. If necessary

this is to be ensured by the installation of safety valves or bursting discs.

Check the connections and joints for leaks to atmosphere at regular intervals (e.g. at every

commissioning) with inert gas and document this check. For this purpose only use suitable

leak detection methods. Never check using a naked flame! If you find leaks, rectify them im-

mediately; the applicable safety regulations are to be observed during this process.

Page 9 of 27

WITT-GASETECHNIK GmbH & Co KG

Salinger Feld 4-8



: +49 (0)2302 89010

www.wittgas.com

Gas Safety- & Control Equipment

D-58454 Witten

Fax: +49 (0)2302 89013

witt@wittgas.com

Also check cables for damage, as well as the supply pipes to the gas mixer and the gas mixer

to the load for leaks.

When using toxic or corrosive gases, for your safety continuously monitor the atmosphere in

the workplace using a gas warning system.

The gas mixer must be used in a well ventilated area. If there is any doubt regarding the venti-

lation then the area should be monitored for minimum oxygen levels and maximum CO2or

flammable gas levels if they are part of the mixture.

A wrong gas mixture may be generated either when the gas mixing unit is started or possibly

as a result of a functional fault during operations, or as a result of the process in the down-

stream system, and for this reason the downstream consumer must be suitable for operations

with wrong gas mixtures. If this is not the case, the gas mixture must be permanently moni-

tored at a suitable place by an analyser to prevent the gas mixture entering a wrong area with-

out having been monitored.

The use of the gas mixer for a purpose other than that intended involves safety risks. Usage for a

purpose other than that intended includes, for example:

Use with gases other than those listed in the technical data.

Operation of the gas mixer with liquids.

The use of the gas mixer in ambient temperatures outside the temperature range specified in

the technical data.

The use of the gas mixer with gases at temperatures outside the temperature range specified

in the technical data.

The installation and operation of the gas mixer in areas with an explosion hazard.

In the case of unauthorised, unapproved changes, modifications, or conversions to the gas mixer,

the guarantee is void.

3.2 Gas mixer with oxygen

Caution!

In the case of the usage of oxygen, the German health and safety regulations BGR 500 Sec.

2.32 must be observed. In particular, the following applies:

The supply pipe for oxygen may only be installed in the connection provided for this purpose.

The oxygen connection must be kept oil-free and grease-free, and also free of soiling.

A vent pipe must be fitted to the safety valve on the receiver (if fitted); this must be designed

such that any gas escaping can flow out without hazard. The vent pipe must be designed such

that the required mass flow rate can be reliably and safely drawn off and the function of the

safety valve is not impaired.

A wrong gas mixture (e.g. pure oxygen) may be generated either when the gas mixing unit is

started or possibly as a result of a functional fault during operations, or as a result of the pro-

cess in the downstream system, and for this reason the downstream consumer must be suita-

ble for operations with wrong gas mixtures (e.g. pure oxygen). If this is not the case, the gas

mixture must be permanently monitored at a suitable place by an analyser to prevent the gas

mixture entering an undefined range without having been monitored.

Observe the maximum control pressure in the technical data.

3.3 Liability

The liability for the function of the unit passes in all cases to the owner or operating organisation as

far as the unit is operated by persons who do not belong to WITT Service, is incorrectly maintained

or repaired, or if the unit is used in a manner that does not comply with the intended usage of the

unit, or is contrary to the applicable regulations.

WITT-GASETECHNIK GmbH & Co KG is not liable for damages arising from failure to observe

these instructions.

Page 10 of 27

WITT-GASETECHNIK GmbH & Co KG

Salinger Feld 4-8



: +49 (0)2302 89010

www.wittgas.com

Gas Safety- & Control Equipment

D-58454 Witten

Fax: +49 (0)2302 89013

witt@wittgas.com

4 Description

4.1 Types

The MG series comprises as standard the types MG 50, MG 100, MG 200 and MG 500. The differ-

ences between the types lie in the mixed gas outputs.

The gas mixer is specified in more detail by further additions. Please see the information in the en-

closed technical data for the specification of your gas mixer (see Section 9).

100

200

500

-2

-3

-4

PvDu

PmDü

Ex Ex-Version (ATEX)

A Analysis

GB Inlet pressure monitoring,

solenoid valve closes on alarm

PvDu Inlet pressure monitoring

PmDü Pilot pressure monitoring

ME elec. pressure switch / solenoid valve

combination

Number of gases

Mixed gas output

Big gas mixer (Gross-Mischer)

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