PIETRO FIORENTINI NORVAL Manual

PRESSURE REGULATOR
NORVAL
TECHNICAL MANUAL MT044
INSTALLATION, COMMISSIONING AND MAINTENANCE INSTRUCTIONS
E

TECHNICAL MANUAL MT044
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Inlet pressure. Outlet pressure.
NORVAL
Issue February 2003

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The PIETRO FIORENTINI SPA with registered office in Milan (Italy) – via Rosellini, 1, declares under its sole
responsibility that the apparatus series Norval bearing the CE marking showed in this manual are designed,
manufactured, tested and inspected in accordance with the provisions of Pressure Equipment Directive 97/23/EC
(PED).
Following conformity assessment procedure has been carried out:
➤EC type-examination (module B) by DVGW (ID n° 0085) – report 02/102/4301/850 issued 12th April 2002
In this report both the versions incorporating the safety shut-off devices series when controlling
overpressure and in-line monitor system which includes a Norval with the function of active
regulator and a 2° Norval with the function of in-line monitor, are classified as safety
accessories according to clause 2.1.3 of art. 1 of PED.
➤Production quality assurance (module D) by BUREAU VERITAS (ID n° 0062) – Attestation d’Approbation
du Sistème Qualité N° CE-PED-D-FIO001-02-ITA issued 15th May 2002.
Further it declares that the classification of the performances characteristics has been verified by DVGW
according to the procedures given by European standard EN 334 and/or by standard DIN 3381. The classification is
detailed in the aforesaid DVGW report.
Arcugnano 25/9/2002 The Pietro Fiorentini SpA
DECLARATION OF CONFORMITY

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GENERAL PRECAUTIONS
- The apparatus described in this manual is a device subject to pressure installed in systems under pressure;
- the apparatus in question is normally installed in systems for transporting flammable gases
(natural gas, for example).
PRECAUTIONS FOR THE OPERATORS
Before proceeding with installation, commissioning or maintenance, operators must:
- examine the safety provisions applicable to the installation in which they must work;
- obtain the authorisations necessary for working when so required;
- use the necessary means of individual protection (helmet, goggles, etc.);
- ensure that the area in which they operate is fitted with the means of collective protection envisaged and
with the necessary safety indications.
HANDLING
The handling of the apparatus and of its components must only be carried out after ensuring that the lifting gear
is adequate for the loads to lift (lifting capacity and functionality). The apparatus must be handled using the
lifting points provided on the apparatus itself.
Motorised means must only be used by the persons in charge of them.
PACKING
The packing for trasportation of equipment and of relevant spare parts are designed and shaped to avoid damage to any
part during transportation, warehousing and handling activities. Therefore the equipment and spare parts shall be kept
into their packing until their installation in the final site. After packing is open, check that no damage occured to any
goods. If damage occured inform the supplier and keep packing for any verification.
INSTALLATION
If the installation of the apparatus requires the application of compression fittings in the field, these must be
installed following the instructions of the manufacturer of the fittings themselves. The choice of the fitting must be
compatible with the use specified for the apparatus and with the specifications of the system when envisaged.
PRECAUTIONS

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COMMISSIONING
Commissioning must be carried out by adequately trained personnel.
During the commissioning activities, the personnel not strictly necessary must be ordered away and the no-go
area must be properly signalled (signs, barriers, etc.).
Check that the settings of the apparatus are those requested; if necessary, reset them to the required values in
accordance with the procedures indicated in the manual.
When commissioning, the risks associated with any discharges into the atmosphere of flammable or noxious
gases must be assessed.
In installations in natural gas distribution networks, the risk of the formation of explosive mixtures (gas/air) inside
the piping must be considered.
CONFORMITY TO DIRECTIVE 97/23/EC (PED)
Pressure regulator Norval is classified as fail open regulator according to the standard EN 334 therefore it is
categorized as pressure accessory according to directive 97/23/EC (PED).
The safety device in-line monitor is categorized as safety accessory according PED. The regulator Norval when
incorporating slam shut valve with pressure switche for overpressure is categorized as safety accessory
according to PED, therefore it can be used both as pressure accessory and safety accessory to PED.
Conformity with Directive 97/23/EC and CE marking of pressure regulator and relevant accessory require
installation in the system with minimum requirements according to: EN 12286.

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1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PAGE 9
1.1 MAIN FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2 NORVAL OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.3 REGULATOR SETTING SPRINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.3.1 REGULATOR SETTING SPRINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.0 INSTALLATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.0 ACCESSORIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.1 RELIEF VALVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.1.1 DIRECT INSTALLATION IN THE LINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.1.2 INSTALLATION WITH ON/OFF VALVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.0 MODULARITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.1 INCORPORATED SLAM-SHUT I-N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.2 SLAM-SHUT SETTING SPRINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.3 NORVAL FUNCTIONING AS A MONITOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.3.1 CHARACTERISTIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.3.2 DIVAL OPERATION WITH MONITOR FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
5.0 START UP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.2 GAS INPUT, CONTROL OF EXTERNAL TIGHTNESS AND SETTING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.3 COMISSIONING THE REGULATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.4 COMMISSIONING THE REGULATOR WITH INCORPORATED I-N SLAM-SHUT . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.5 COMMISSIONING THE REGULATOR PLUS NORVAL IN-LINE MONITOR
WITH INCORPORATED I-N SLAM-SHUT VALVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.0 TROUBLE-SHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.1 REGULATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.2 REGULATOR SLAM-SHUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
7.0 MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.2 NORVAL REGULATOR MAINTENANCE PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.3 NORVAL REGULATOR + I-N MAINTENANCE PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
7.4 MAINTENANCE PROCEDURE FOR THE NORVAL REGULATOR + I-N + ER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
8.0 FINAL OPERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
8.1 THIGHTNESS AND SETTING CHECKS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
8.2 START UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
9.0 LIST OF RECOMMENDED SPARES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
INDEX

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1.0 INTRODUCTION
The scope of this manual is to provide the essential information for the installation, commissioning, disassembly,
re-assembly and maintenance of NORVAL regulators.
It is also appropriate to provide a brief illustration of the main features of the regulator and of its accessories.
1.1 MAIN FEATURES
The NORVAL pressure regulator is a pressure regulator for previously cleaned gaseous fluids and is suitable for
medium and low pressures.
The NORVAL is a normally open regulator and consequently opens in the event of:
- breakage of the main diaphragm
- no regulated pressure signal
The main specifications of this regulator are:
• Design pressure: up to 16 bar;
• Operating temperature range: -20 °C to 60 °C;
• Ambient temperature: -20 °C to 60 °C;
• Inlet pressure range bpe:
0.1 to 16 bar for DN 1" to 3"
0.1 to 8 bar for DN 4" to 8"
• Regulating range possible Wh:
0.0075 to 4.4 bar for DN 1" to 4"
0.012 to 1.8 bar for DN 6" to 8"
• Precision class AC: up to 5;
• Closing pressure class SG: up to 10.
1.2 OPERATION
NORVAL series regulators (Fig.1) are spring actuated devices with control of the downstream pressure by means
of an external sensing line 1.
The downstream pressure is controlled by means of the equilibrium between the action of the spring 2 and the
action exerted by the downstream pressure on the diaphragm 3.
The movement is transmitted by the shaft 4 to the obturator 5 which moves perpendicularly to the gas flow
direction. Hermetic tightness is ensured by a rubber gasket fixed to the obturator.
Regulation is therefore obtained from the confrontation between the load of the setting spring 2 and the thrust on
the diaphragm 3 deriving from the downstream pressure.
If during operation, for example, there is a drop in the downstream pressure Pa below the set-point (as a result of
an increase in the requested flow rate or a drop in the upstream pressure) an imbalance is created which causes
the obturat or 5 to open and therefore an increase in the flow until the downstream pressure
reaches the set-point again. Vice versa, when the downstream pressure rises above the set-point (as a result of
a drop in the requested flow rate or an increase in the upstream pressure) the obturator 5 closes and the flow
rate drops until the downstream pressure reaches the set-point again.

TECHNICAL MANUAL MT044
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5
Pe
41
3
2
74
Pa
Fig. 1

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1.3 TAB. 1 Standard Regulator Setting Springs (Fig. 2)
2701623 WHITE 4.0 9.00 11.00 7.5 ÷ 9.5 9.5 ÷ 11 12 ÷ 15
2701700 YELLOW 4.2 9.00 11.00 8.5 ÷ 11 10.5 ÷ 12 13 ÷ 17
2701863 ORANGE 4.5 9.00 11.00 10 ÷ 13 12 ÷ 14 15 ÷ 21
2701966 RED 350 4.8 9.50 11.50 11 ÷ 16 13 ÷ 17 16 ÷ 23
2702205 GREEN 5.0 9.00 11.00 12 ÷ 17 11 ÷ 19 21 ÷ 29
2702385 BLACK 5.5 10.50 12.50 15 ÷ 21 16 ÷ 24 25 ÷ 35
2702565 BLUE 6.0 11.50 13.50 19 ÷ 27 20 ÷ 28 31 ÷ 42
2702755 WHITE 6.5 8.50 10.50 21 ÷ 36 22 ÷ 37 38 ÷ 60 80 ÷ 120
2702975 YELLOW 7.0 8.50 10.50 28 ÷ 48 30 ÷ 50 55 ÷ 83 75 ÷ 85 115 ÷ 170
2703175 ORANGE 7.5 9.25 11.25 43 ÷ 63 45 ÷ 65 80 ÷ 110 155 ÷ 230
2703360 RED 85 8.0 9.00 11.00 53 ÷ 80 55 ÷ 80 95 ÷ 135 190 ÷ 280
2703525 GREEN 300 8.5 9.00 11.00 125 ÷ 170 250 ÷ 360
2703745 BLACK 9.0 9.00 11.00 150 ÷ 220 300 ÷ 430
2703895 BLUE 9.5 9.50 11.50 170 ÷ 260 360 ÷ 500
2704062 BROWN 10.0 9.00 11.00 230 ÷ 340 470 ÷ 720
2704400 AZURE 11.0 9.50 11.50 300 ÷ 500 680 ÷ 950 680 ÷ 950
2704515 WH.-YELL. 11.5 9.25 11.25 400 ÷ 530 850 ÷ 1100
2704390 GREEN 11.0 7.50 9.50 900 ÷ 1600
2704615 BLUE 260 12.0 8.00 10.00 900 ÷ 1250 1450 ÷ 2400
2704820 VIOLET 13.0 8.00 10.00 1200 ÷ 1950 2100 ÷ 3150
2704910 AZURE 14.0 8.00 10.00 1800 ÷ 2800 3000 ÷ 4400
Springs characteristics SETTING RANGE in mbar
Covers
CodE Colour De Lo d i it
Ø 630 Ø 495 Ø 375 Ø 375 TR
DN: DN: DN: DN: DN: DN: DN:
2”1/2- 3” 4” 1” ÷ 2” 2”1/2÷4” 1”÷2” 2”
1/2÷4” 1”÷4”
De = Ø external diameter d = Ø wire diameter i= active coils Lo = spring length it = total coils
2702599 WHITE 100 6.0 10.5 12.5 12 ÷ 14.5
2702790 YELLOW 100 6.5 11.5 13.5 14 ÷ 18
2703015 ORANGE 100 7.0 12.0 14.0 17 ÷ 21
2703199 RED 100 7.5 12.5 14.5 20 ÷ 25
2703380 GREEN 100 8.0 12.5 14.5 24 ÷ 31
2703560 BLACK 100 8.5 12.0 14.0 30 ÷ 39
2703827 BLUE 100 9.0 11.5 13.5 38 ÷ 49
2703930 BROWN 100 9.5 11.0 13.0 47 ÷ 62 75 ÷ 100
2704108 VIOLET 100 10.0 10.5 12.5 60 ÷ 79 95 ÷ 130
2704440 AZURE 100 11.0 11.0 13.0 125 ÷ 170
2704670 WH.-YELL. 100 400 12.0 10.5 12.5 165 ÷ 230 220 ÷ 300 390 ÷ 535
2704108 VIOLET 100 10.0 10.5 12.5 210 ÷ 280 280 ÷ 360 500 ÷ 650
2703720 WHITE 65 9.0 15.5 17.5
2704440 AZURE 100 11.0 11.0 13.0 270 ÷ 330 330 ÷ 420 600 ÷ 750
2703720 WHITE 65 9.0 15.5 17.5
2704670 WH.-YELL. 100 12.0 10.5 12.5 320 ÷ 405 400 ÷ 520 700 ÷ 930
2703720 WHITE 65 9.0 15.5 17.5
2704670 WH.-YELL. 100 12.0 10.5 12.5 500 ÷ 650 900 ÷ 1310
2704210 RED 65 10.5 15.5 17.5
2704985 WH.-YELL. 100 14.0 11.0 13.0 1290 ÷ 1800
2704210 RED 65 10.5 15.5 17.5
Ø 817 Ø 658 Ø 630 Ø 495
DN: 6” ÷ 8” DN: 6” ÷ 8” DN: 6” ÷ 8” DN: 6” ÷ 8”

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1.3.1 TAB. 2 Upturned Regulator Setting Springs (Fig. 3)
2701966 RED 4.8 9.50 11.50 8 ÷ 12
2702205 GREEN 5.0 9.00 11.00 9 ÷ 13 9 ÷ 12 10 ÷ 17
2702385 BLACK 350 5.5 10.50 12.50 12 ÷ 15 11 ÷ 15 14 ÷ 22
2702565 BLUE 6.0 11.50 13.50 14 ÷ 18 14 ÷ 19 20 ÷ 28
2702755 WHITE 6.5 8.50 10.50 17 ÷ 28 16 ÷ 26 25 ÷ 45 80 ÷ 120
2702975 YELLOW 7.0 8.50 10.50 25 ÷ 40 22 ÷ 40 40 ÷ 70 60 ÷ 70 115 ÷ 170
2703175 ORANGE 7.5 9.25 11.25 35 ÷ 45 35 ÷ 55 65 ÷ 90 65 ÷ 95 155 ÷ 230
2703360 RED 8.0 9.00 11.00 45 ÷ 67 50 ÷ 70 80 ÷ 120 190 ÷ 280
2703525 GREEN 300 8.5 9.00 11.00 62 ÷ 90 62 ÷ 90 110 ÷ 155 250 ÷ 360
2703745 BLACK 85 9.0 9.00 11.00 135 ÷ 205 315 ÷ 470
2703895 BLUE 9.5 9.50 11.50 155 ÷ 245 360 ÷ 540
2704062 BROWN 10.0 9.00 11.00 215 ÷ 325 470 ÷ 720 470 ÷ 720
2704400 AZURE 11.0 9.50 11.50 285 ÷ 500 680 ÷ 1050 680 ÷ 1050
2704040 ORANGE 10.0 8.00 10.50
2704390 GREEN 11.0 7.50 9.50 900 ÷ 1600
2704615 BLUE 260 12.0 8.00 10.00 900 ÷ 1400 1450 ÷ 2400
2704820 VIOLET 13.0 8.00 10.00 1200 ÷ 1950 2100 ÷ 3150
2704910 AZURE 14.0 8.00 10.00 1800 ÷ 1050 3000 ÷ 4400
De = Ø external diameter d = Ø wire diameter i= active coils Lo = spring length it = total coils
Springs characteristics SETTING RANGE in mbar
Covers
Code Colour De Lo d i it
Ø 630 Ø 495 Ø 375 Ø 375 TR
DN: DN: DN: DN: DN: DN: DN:
2”1/2- 3” 4” 1” ÷ 2” 2”1/2÷4” 1”÷2” 2”
1/2÷4” 1”÷4”
2703380 GREEN 100 8.0 12.5 14.5 8 ÷ 13
2703560 BLACK 100 8.5 12.0 14.0 12 ÷ 21
2703827 BLUE 100 9.0 11.5 13.5 20 ÷ 31
2703930 BROWN 100 9.5 11.0 13.0 29 ÷ 45
2704108 VIOLET 100 10.0 10.5 12.5 42 ÷ 71 75 ÷ 110
2704440 AZURE 100 11.0 11.0 13.0 65 ÷ 95 100 ÷ 150
2704670 WH.-YELL. 100 12.0 10.5 12.5 140 ÷ 210 190 ÷ 270 340 ÷ 480
2704108 VIOLET 100 10.0 10.5 12.5 190 ÷ 260 250 ÷ 330 450 ÷ 600
2703720 WHITE 65 400 9.0 15.5 17.5
2704440 AZURE 100 11.0 11.0 13.0 250 ÷ 310 300 ÷ 390 550 ÷ 700
2703720 WHITE 65 9.0 15.5 17.5
2704670 WH.-YELL. 100 12.0 10.5 12.5 300 ÷ 405 370 ÷ 490 650 ÷ 880
2703720 WHITE 65 9.0 15.5 17.5
2704670 WH.-YELL. 100 12.0 10.5 12.5 470 ÷ 600 850 ÷ 1260
2704210 RED 65 10.5 15.5 17.5
2704985 WH.-BLUE 100 14.0 11.0 13.0 1240 ÷ 1800
2704210 RED 65 10.5 15.5 17.5
Ø 817 Ø 658 Ø 630 Ø 495
DN: 6” ÷ 8” DN: 6” ÷ 8” DN: 6” ÷ 8” DN: 6” ÷ 8”

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2.1 GENERAL
Pressure regulator does not require any supplementary upstream safety accessory for protection against
overpressure compared with its design pressure PS, when upstream reducing station is sized for a max
downstream incidental pressure MIPd ≤1,1 PS.
Before installing the regulator it is necessary to ensure that:
- the regulator can be inserted in the space provided and that subsequent maintenance operations will be
sufficiently practicable;
- the upstream and downstream piping is at the same level and capable of supporting the weight of the regulator;
- the inlet/outlet flanges of the piping are parallel;
- the inlet/outlet flanges of the regulator are clean and the regulator itself has not been subject to damage during
transport;
- the piping upstream has been cleaned to expel residual impurities such as welding scale, sand, paint residues,
water, etc.
The normally raccomended set-up is:
2.0 INSTALLATION
Fig. 2 (Standard Regulator) Fig. 3 (Upturned Regulator)
TAB. 3 CONNECTING THE APPARATUS
IN-LINE INSTALLATION
Regulator
Sensing line
Control pressure gauge
Bleed cock
On/Off valve
The connections between the apparatus and the main piping must be made using stainless steel or cooper pipe
with minimum internal diameter of 12 mm.

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INSTALLATION AT RIGHT ANGLES
TAB. 4 DETAIL OF MULTIPLE TAKE-OFF
Regulator
Sensing line
Control pressure gauge
Bleed cock
On/Off valve

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The regulator must be installed in the line with the arrow on the body pointing in the gas flow direction.
It is indispensable for good regulation for the position of the downstream pressure take-offs and the speed of the
gas at the take-off point to respect the values given in tables 3 and 4 (positioning) and 5 (speed).
The pressure regulator, when installed on a reducing station, shall be installed at least according to the
requirements of standard EN 12186.
All venting connections shall be connected as required by above mentioned standard.
The following is recommended so as to prevent the accumulation of impurities and condensate in the lines of the
pressure take-offs:
a) the lines themselves must slope down towards the downstream piping with a slope of about 5-10%;
b) the connectors on the piping must always be welded on the top of the piping itself and there must be no burr
or inward protrusions in the hole in the piping.
NB. WE RECOMMEND NOT TO PUT ON/OFF VALVES ON THE IMPULSE TAKE-OFFS
TAB. 5
The speed of the gas must not exceed the following values in the piping downstream from the regulator:
Vmax = 25 m/s for 1,5 < Pa < 4 bar
Vmax = 20 m/s for 0,5 < Pa < 1,5 bar
Vmax = 15 m/s for Pa < 0,5 bar
DOWNSTREAM VOLUME REQUIRED FOR INSTALLATION
In the case of a service regulator of the ON-OFF type (stopping or starting of burners), you should remember that
though the NORVAL apparatus is classified as being of the fast reaction type, it requires an appropriately
dimensioned volume of gas between the apparatus itself and the burner so as to partly absorb the pressure swings
caused by fast flow rate variations.

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3.0 ACCESSORIES
3.1 RELIEF VALVE
The relief valve is a safety device which releases a certain quantity of gas to the exterior when the pressure at the
control point exceeds the set-point as a result of short-lasting events such as, for example, the very fast closing
of the on/off valves and/or overheating of the gas with zero flow rate demand. The release of the gas to the
exterior can, for example, delay or block the intervention of the slam-shut valves for transitory reasons deriving
from damage to the regulator.
Obviously the quantity of gas released depends on the extent of the overpressure with respect to the set-point.
The different models of relief valves available are all based on the same operating principle which is illustrated below
with reference to the valve VS/AM 55 (fig. 4).
It is based on the contrast between the thrust on the diaphragm 24 deriving from the pressure of the gas to
control and the thrust from the setting spring 20. The weight of the mobile assembly, the static thrust and the
residual dynamic thrust on the obturator 4 also contribute to this contrast. When the thrust deriving from the
pressure of the gas exceeds that of the setting spring, the obturator 4 is raised and a certain quantity of gas is
released as a result.
As soon as the pressure drops below the set-point, the obturator returns to the closed position.
Proceed as indicated below to control and adjust intervention of the relief valve.
Fig. 4

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3.1.1 DIRECT INSTALLATION IN THE LINE (Fig. 5)
When the relief valve is fitted directly in the line that is, without the interposition of an on/off valve, we recommend
proceeding as follows:
1) ensure that the downstream on/off valve V2 and the bleed cock 6 are closed;
2) increase the pressure in the downstream section to the value at which intervention should occur by connecting
a controlled auxiliary pressure to the cock 6 and stabilise it at the desired value;
3)check intervention of the relief valve and adjust it if necessary by turning the internal adjustment ring 14
appropriately (clockwise to increase the set-point, anticlockwise to reduce it).
3.1.2 INSTALLATION WITH ON/OFF VALVE (Fig. 6)
1)Close the on/off valve 16;
2)connect a controlled auxiliary pressure to the take-off 17 and increase it slowly to the envisaged intervention
value;
3)check the intervention of the relief valve and adjust it if necessary by turning the internal adjustment ring 14
appropriately (clockwise to increase the set-point, anticlockwise to reduce it).
Fig. 6Fig. 5

TECHNICAL MANUAL MT044
18
The modular-type conception of NORVAL series regulators means that it is also possible to fit the slam-shut
incorporated with the body itself even after the installation of the regulator.
Furthermore, the regulator can be adapted for operation as an in-line monitor by installing a special device.
4.1 INCORPORATED SLAM-SHUT I-N
This is a device (fig. 7) which immediately blocks the gas flow if, following some kind of failure, the downstream
pressure reaches the set-point for its intervention or if it is operated manually.
The main characteristics of the slam-shut device are:
• design pressure: 18.9 bar for all the components;
• intervention with pressure increase and/or decrease;
• intervention accuracy (AG): ± 1% of the pressure set-point for pressure increases, ± 5% for pressure decreases;
• incorporated by-pass for balancing the pressures and facilitating the resetting of the device.
• push-button manual control.
4.0 MODULARITY
...+ I-N SLAM-SHUT
Fig. 7

TECHNICAL MANUAL MT044
19
The slam-shut mechanism consists of:
• a mobile obturator A with sealing gaskets subject to the load of the closing spring G;
• a lever assembly L whose rotation causes the movement of the obturator A;
• a pressure switch device I-N whose internal motion determines the open or closed position of the obturator A.
The pressure switch device (fig. 8) comprises a control head 11 in which the pressure to control Pa acts on the
diaphragm 21 which is integral with the shaft with cams 18.
The load of the pressure Pa on the diaphragm is contrasted by the springs 14 and 15, which respectively determine
intervention for a pressure increase or decrease.
The slam-shut device is set by adjusting the rings 12 and 13.
The intervention value is increased by turning the rings clockwise and vice versa when turned anticlockwise.
In the case of intervention for pressure increase, when the Pa exceeds the set-point, the load on the diaphragm
21 of the control head B increases until it overcomes the resistance of the spring 14 .
This provokes the downward displacement of the shaft 18 which shifts the feeler 19 and releases the lever
mechanism 20 by means of the cam 23.
Intervention for a pressure decrease takes place as follows.
As long as the value of Pa stays above the set load of the spring 15, the spring support 17 rests on support 16.
If the pressure Pa drops below the set-point, the support of spring 16 stops its stroke on the beat of the body 5
and the spring 15 displaces the support 17 upwards and the shaft 18 as a result. The cam 24 then shifts the feeler
19 and causes the release of the lever mechanism 20.
Intervention of the slam-shut device can also be provoked manually by means of the release button 22. The
connection between the control head 11 and the Pa control point can be made with the interposition of a device
(Push) fig. 14 which makes it easy to control the operation of the pressure control device.
Fig. 8a Fig. 8b

TECHNICAL MANUAL MT044
20
4.2 TAB. 6 SLAM-SHUT SETTING SPRINGS
Fig. 9
2700565 WHITE 2.0 5.25 7.25 13 ÷ 33 17 ÷ 35
2700675 YELLOW 2.3 5.25 7.25 25 ÷ 50 30 ÷ 55
2700820 ORANGE 2.5 5.00 7.00 40 ÷ 85 45 ÷ 85
2700910 RED 2.7 6.00 8.00 65 ÷ 145 65 ÷ 145
2701035 GREEN 3.0 5.25 7.25 100 ÷ 180 100 ÷ 180
2701140 BLACK 35 50 3.2 4.50 6.50 150 ÷ 270 150 ÷ 270
2701255 BLUE 3.5 4.50 6.50 200 ÷ 350 200 ÷ 350
2701380 GREY 3.7 4.25 6.25 700 ÷ 1500
2701525 BROWN 4.0 4.50 6.50 300 ÷ 550 300 ÷ 550 900 ÷ 2000
2701645 VIOLET 4.2 4.00 6.00 500 ÷ 900 500 ÷ 900 1300 ÷ 2800
2702065 AZURE 5.0 4.50 6.00 850 ÷ 1200 850 ÷ 1200 2500 ÷ 5000
SETTING RANGE mbar
Springs characteristics I-N (Fig. 9) I-N (Fig. 10) I-N/TR (Fig. 9 and fig. 10)
Code Colour De Lo d i it max min max min max min
2700338 WHITE 1.3 8.75 10.75 5 ÷ 19 8 ÷ 23
2700377 YELLOW 1.5 8.50 10.50 15 ÷ 50 20 ÷ 50
2700464 ORANGE 40 1.7 8.50 10.50 45 ÷ 100 45 ÷ 100
2700513 RED 15 2.0 8.50 10.50 70 ÷ 140 70 ÷ 140
2700713 GREEN 2.3 8.50 10.50 120 ÷ 270 120 ÷ 270 150 ÷ 1550
2700750 BLACK 2.5 6.00 8.25 250 ÷ 600 250 ÷ 600 1000 ÷ 2100
2700980 BLUE 35 3.0 6.00 8.00 500 ÷ 900 500 ÷ 900 1800 ÷ 2700
2701180 BROWN 3.5 6.25 8.25
De = Ø external diameter d = Ø wire diameter i= active coils Lo = spring length it = total coils
Fig. 10