Witt NGX User manual

Date: 02/2018
W 4651-6.10e
page 1 / 5 MW - Pr
INSTRUCTIONS
Maximum level switch NGX
Please read the entire manual carefully before installing or operating a maximum level switch!
1. INTENDED USE
The maximum level switch NGX with TÜV design approval
(certificate No. 968/EL 743.00/11) is designed to protect
compressors within a refrigeration plant against liquid hammer
(e.g. to conform with TRAS110). The maximum level switch is
not suitable to be used as a minimum level switch or level switch.
2. SAFETY REQUIREMENTS
Trained and knowledgeable personnel experienced in installation
and service of refrigeration systems must carry all of the work
within refrigeration plants out. All safety regulations and codes of
practice concerning the use of refrigerants must be adhered to.
Regulation EN 378 must be followed.
Frequently (once a year, or with contaminated plants even more often) you should check whether
debris or metal chips from the plant have connected to the float of the NGX. Check paricularly 2
weeks and 4 weeks after start-up and upon each acting of the NGX.
When installing the maximum level switch you should ensure that the execution is at least IP54.
Special attention should be paid to protection clothing and wearing of safety glasses, especially
when checking the functioning and when disassembling the NGX.
A functioning check is only permitted when the level is below the maximum level in the
pressure vessel!
3. TERMS OF WARRENTY
To avoid accidents and for your safety you should operate the maximum level switch solely for the intended
use. No modifications or conversions may be carried out to the NGX without the explicit written approval of
TH. WITT Kältemaschinenfabrik GmbH.
Our liability of warranty is void if:
•The instructions were not followed
•The NGX is operated incorrectly or is installed contrary to these installation instructions
•The NGX is used for applications other than that for which it was intended
•There have been modifications made without written approval
•Safety regulations or codes of practice have been ignored
•The wiring diagram as per page 3 of the instructions for the relay BR-NWt W 4651-6.11 are not adhered
to (as this is part of the design approval)
4. RANGE OF OPERATION
The mechanical operated NGX can be used on surge drums and liquid receivers and is suitable for all
common refrigerants with a density ρof at least 600 kg/m³. Even when electrical level switches are installed,
the use of the design-approved NGX, to switch off the compressors, is mandatory.
5. SCOPE OF DELIVERY (STANDARD)
•Sensor NGX with junction box
•Brackets to connect the NGX to the 1“ connection of the stop valve
•Stop valve EA 32 - G1“-I
•Relay BNRt (for installation in the switch gear, see installation instructions W 4651-6.11-)
Optional
•Stop valve in stainless steel
•Socket connection G 1“-NGX (when used with foreign valves)

Date: 02/2018
W 4651-6.10e
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INSTRUCTIONS
Maximum level switch NGX
6. TECHN. DATA
NGX- part list
Part no.
Dimension
Amount
Part no.
switch
1
NGX
1
4651.000006
crew cap
2
Ø 10,7
1
---------
name plate
3
------
1
---------
blind rivet
4
3,0x6,0
1
---------
solenoid switch
5
Typ MRS
1
4692.000003
junction box complete
6
------
1
4651.000005
screw joint
7
M16x1,5
2
---------
light emitting diode (LED)
8
Typ LD32
1
---------
circuit board
9
------
1
---------
sleeve
10
Typ 0.75-14
2
---------
mounting plate
11
------
1
---------
cylinder head screw
12
M4x16
2
---------
tube clamp (Brocket)
13
1 ¼“
1
5831.000002
cylinder head screw
14
M6x60
1
5112.000041
o - seal
15
Ø 28x5
1
5642.000014
balancing bar
16
------
1
---------
NGX- replacement parts
NGX without valve and without BNRt
--
------
--
4651.000013
NGX complete with valve + BNRt
--
------
--
4651.000015
NGX complete with valve without BNRt
--
------
--
4651.000016
NGX complete without valve + BNRt
--
------
--
4651.000017
NGX with stainless steel connection, without valves + BNRt
--
------
--
4651.000019
NGX with stainless steel connection, without valves or BNRt
--
------
--
4651.000020
NGX with stainless steel connection + valves + BNRt
--
------
--
4651.000026
NGX with stainless steel valves without BNRt
--
------
--
4651.000027
NGX with stainless steel conn. without valves with BNRt
--
------
--
4651.000031
NGX with stainless steel conn. without valves and BR-NWt
--
------
--
4651.000032
All NGX complete replacement assemblies are also available in a 40 bar execution. The last 0 in the article number
should then be replaced by a 1, e.g.
NGX without valve and without BNRt, 40 bar execeution
--
------
--
4651.000113

Date: 02/2018
W 4651-6.10e
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INSTRUCTIONS
Maximum level switch NGX
A) Switch
Housing material: 1.4571
Balancing bar: PTFE/
Connection: G 1“ outer thread
Pressure- / Temp.-Range: PB 25 bar / +80°C to –50°C
Weight: 0,6 kg
B) Junction box
Material: Aluminium
Dimensions: 63 x 58 x 40 mm
Protection Class: IP 65
Connections: 2 x PG 9
Weight: . 0.36 kg (Junction box with brackets)
C) Brackets
Material: PP - black
Dimensions: 60 x 71 x 30 mm, hole approximately ø 42 mm
With EA 32 /G1” or EA 40/G1” valve
D) Reed-Contact
Voltage: 14 V AC/DC
Current: max. 0.5 A
Cycles: 1000 / s
Contact: Rhodium
M16x1,5
EA 32/G1“-I
LED
NGX
ca 290
40
42,4x2,6
a) Standard execution
M16x1,5
EA 40/G1“- I
LED
NGX
ca 350
65
48,4x2,6
b) Stainless Steel execution
7. DESCRIPTION OF OPERATION
The switching activating point is located in the center line. Therefore the center line of the mximum level
switch determines the maximum level in the vessel that is used for the control. In the NGX housing there is a
balancing bar, which consists on one side of PTFE and on the other side there is a magnet fitted (these are
the only materials in contact with refrigerant). When the refrigerant level rises within the surge drum to the
connection of the NGX, the PTFE float will get in contact with refrigerant and start to drift up. The magnet on
the other side of the balancing bar will move downwards. A reed-contact that is installed outside of the
refrigerant surrounding will recognize the position of the magnet and will open when about 4mm are passed
in the bottom position. The signal will be transferred through the relay BR-NWt and an auxiliary contactor
within the switchgear to the compressor control.
An LED display connected in series with the reed-switch is illuminated during normal operation. If the LED is
not illuminated the following reasons might occur:
•The maximum level in the surge drum has been exceeded
•The power supply was interrupted (cable breakage or misconnected cable)
•The reed-contact is defect

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INSTRUCTIONS
Maximum level switch NGX
•The magnet has been contaminated (with metal particles).
The NGX cannot be connected directly to a SPS control. (If the wiring diagram as shown on page 3
of the installation instructions of the BR-NWt W 4651-6.11 is modified, the design approval is void)
8. TRANSPORT AND STORAGE
All openings (connections, etc.) are covered with yellow protection caps to prevent the intake of moisture or
dirt. Storage or transportation of sensor and relay should be dry at all times. Pay special attention that no
metal particles can enter the NGX housing to prevent the magnet may get weight down.
9. INSTALLATION
If the standard NGX is ordered there should be a DN 32 (42,4 x 3,2 mm) connection at the surge drum at the
height of the desired level, to weld on the supplied stop valve EA 32.
When a stainless steel execution has been ordered a DN 40 (48,3 x 3,2 mm) connection has to be fitted to
the surge drum at the relevant height of the maximum allowable level.
The sensor should not be fitted directly into the connection of the surge drum, because the
balancing bar would interfere with the boiling refrigerant.
If a different brand valve should be used, a threaded connection G1“-NGX should be ordered, in which the
NGX can be screwed. Please ensure that the liquid refrigerant can reach the balancing bar unhindered and
the inner diameter of the connection to the surge drum is at least 35 mm. The connection to screw in the
NGX showed be sized in such a way that the balancing bar cannot touch the valve seat.
Screw back the counter nut to the end position so you can install the NGX into the seat connection of the EA
32 (take care that the O-ring will not get damaged!). When the installation is finished the cable outlet should
face vertical down. When tightening the counter nut you will achieve a seal similar to a packing box. With the
bracket you may connect the junction box to the valve, whereas the cable connections should face
downwards. Pay attention that the LED is visible at all times!
The electrical connections should be executed according to the wiring diagram as shown in the installation
instructions of the relay BR-NWt W 4651-6.11:
In addition to the limit-contact-relay BR-NWt you will require an auxiliary contactor and a reset switch, which
are not within the scope of delivery. Furthermore it is recommended to install a fault signal indication.
When the maximum level switch NGX shall be used without the relay BR-NWt, only safety extra low voltage
(SELV oder PELV) should be provided to activate the magnet switch.
All electrical connections must we executed by a certified electrician familiar with the system, who is
familiar with the standards and local regulations, e.g. BGV A2 (VBG 4), VDE 0100, VDE 0113 (EN
60204 T1) und VDE 0660 T5 (EN 60439 T1) or equivalent.
10. COMMISSIONING AND START-UP
Operate the maximum level switch NGX only when you are sure that all connections have been installed
properly and the following tests have been executed.
Functioning check:
Turn the housing of the NGX 180°, by carefully loosening the counter nut ¼ turn. On the nameplate you
should be able to read the word “Prüfstellung” in the proper position. If the balancing bar is not obstructed it
will fall down and the magnet will release the reed contact. The red LED will switch off.
Adjusting the limit-contact-relay BR-NWt
See installation instructions fort he relay BR-NWt W 4651-6-11.

Date: 02/2018
W 4651-6.10e
page 5 / 5 MW - Pr
INSTRUCTIONS
Maximum level switch NGX
11. OPERATION
The NGX operates as explained before and will switch off the compressor(s) if the relevant maximum level
has been exceeded. The cutout of the compressors should be executed per hardware by means of an
auxiliary contactor (K). Any other wiring or control scheme is only possible in areas where BGR 500 (formerly
VGB 20), or equivalent codes, must not be adhered to.
12. MAINTENANCE AND INSPECTION
A functioning check, as described above, should be executed frequently (once a year or if required
more often), particularly when the NGX has been activated.
If the magnet has become contaminated with metal particles from the system, close the stop valve EA 32
and remove the sensor by carefully screwing the unit out in order to clean the balancing bar with the magnet
thoroughly. We recommend sending in the sensor back to the manufacturer for repair and proper
adjustment.
When removing the NGX or during the functioning check you should always wear protective clothing
as per codes of practise, e.g. EN 378.
13. APPROVALS / REGULATIONS
Design Approval
The maximum level switch has passed a design test by TÜV Rheinland and has received certificate No.
968/EL 743.00/11. The design approval includes maximum level switch NGX and relay BR-NWt in
conjunction with the wiring diagram shown (page 3 of the BR-NWt instructions W 4651-6.11).
EU-Conformity declaration
We declare that we have conformed with the relevant European regulations 2004/108/EG (EMV-directive)
and 2006/95/EG (low-voltage-directive), provided the NGX is operated according to the intended use.
The following standards were considered for the design approval:
TRAS 110:11/2008 safety requirements for ammonia refrigeration systems
EN 378-2:2008+A1:2009 refrigerant systems and heat pumps
BGR 500, chapter2.35:03/2007 codes of the employers mutual insurance association regarding safety and
health –operation of refrigeration and heat pump systems
EN ISO 13849-1:2008+AC:2009 (extracts) safety of machinery –safety relevant parts of control systems
EN 61508, part 1 to 7:2010 (extracts) functional safety of safety relevant electrical/electronic programmed
systems
EN 50178:1997 equipment of high voltage systems
A technical documentation as well as the report of the design approval is available.
The maximum level switch NGX achieves performance level (PL) c/category 1 per DIN EN ISO 13849-1 and
safety level SIL 1 according to IEC 61508. The maximum level switch is a device to protect machinery; it is
not intended for the safety of personnel.
Aachen, 14.04.2011 Monika Witt - Geschäftsführerin -
Ort Datum Unterzeichner Unterschrift