NVFN Series
Flamstop fuel shut-off valves
Technical Data Sheet
WattsWater.eu
Description
NVFN
FLAMSTOP
1/2” and 3/4” liquid and gas fuel shut-off valves, suitable for biodiesel. Positive action
with manual resetting. Liquid expansion thermostat. Compact sensor. 1/2”M sensor
sheath connection (with 1/2”F x 3/4”M nipple). INAIL approved and set. Compliant with
Directives PED 2014/68/EU and ATEX 2014/34/EU.
Type Part No. DN bar
NVFN 0231415 1/2” FF 10
NVFN 0231420 3/4” FF 10
NVFN 0231425 1” FF 10
NVFN 0231432 1.1/4” FF 10
NVFN 0231440 1.1/2” FF 10
NVFN 0231450 2” FF 10
NVFN 0231465 65 10
NVFN 0231480 80 10
Technical features
Setpoint temperature 97°C (±3°C)
Maximum temperature, sensor side 120°C
Maximum temperature, valve side 50°C
Maximum operating pressure 6 bar (NVFN 15-25) - 1 bar (NVFN 32-80)
Fuels Diesel, fuel oil, natural gas, propane, butane
Capillary length 5 m
Minimum storage temperature -40°C
Operating range 10-100°C
Minimum temperature, valve side -5°C
Minimum temperature, sensor side -15°C
N.B. The NVFN15 and NVFN20 models with FPM seals can also be used for biodiesel.
Features
Body Die-cast aluminium (NVFN 15-50) - Cast aluminium (NVFN 65-80)
Seals FPM (NVFN 15-20) - NBR (NVFN 25-80)
Disc spring AISI304 stainless steel
Capillary Electrolytic copper
Heat-sensitive element Liquid expansion
Connections (1/2” to 2” models) FF threaded gas (ISO 228/1)
Connections (DN65 and DN80 models) PN16 flanged (UNI 2223)
Test points (1/2”-2” mod.) Qty. 2 x 1/4”
Test points (DN65 and DN80) Qty. 4 x 1/4”
Heat-sensitive element sheath connection G 1/2”M (ISO 228/1)
Approvals
Approved to “R” regulations (2009 edition). Calibration certificate issued by lNAIL.
In certain cases, INAIL regulations (R regulations, 2009 Edition) governing systems with boilers with heat output exceeding
35kW, require the use of a fuel shut-off valve in place of a thermal drain valve. They define a "fuel shut-off valve" as: “a positiveaction valve, which automatically shuts off the flow of fuel if the water overheats, so that it does not exceed the established
safety temperature”. The fuel shut-off valve is a self-operated positive-safety device (operating without the use of external
energy).
Application
According to the provisions of R regulations Ed. 2009, the technical specification for the application of Title II of Italian Ministerial
Decree 1/12/75 pursuant to art. 26 of the said decree concerning "central heating systems using pressurised hot water at a
temperature not exceeding 110°C and maximum overall rated power of the space heaters (or maximum overall heat output
of the space heaters) greater than 35 kW", the use of fuel shut-off valves is required in the following cases: systems with
closed expansion vessel (CHAP. R.3.B., point 1., letter b); closed-vessel systems with heat exchangers supplied with fluids
at temperatures exceeding 110°C to the primary circuit (CHAP. R.3.D., point 2.2.1., letter g); - systems with modular boilers
(Chap. R.3.F.).
2
Operation
1000
500
200
100
10
20
50
100 200 500 1.000 2.000 5.000 10.000 20.000 50.000
DN32
DN25
DN15
PRESSURE DROP
100200 500 1000 2000 5000 10000 50000
3
5102050 100
200 500 1000
DN20
DN40
DN50
DN65
DN80
FLOW RATE
[
mm c.a.
]
Q (kg/h) - Gasolio
Q (kg/h) - Olio combustibile
(3÷5 °E)
Q (Nm
3
/h) - Metano
(d=0,583)
When the setpoint temperature is reached, the heat-sensitive element (4) causes the grooved piston supporting the stem with
integral disc (2) to move, causing the stem to drop, thus closing the valve. Valve closing is not gradual: the valve snaps shut
when the setpoint temperature is reached, so the fuel flow is not throttled. It is not possible to reset the valve until the water
temperature has fallen below 85°C.
1
Characteristics
1) Resetknob
2) Disc
3) Cover
2
3
6
5
4
4) Heat-sensitive element
5) Valve body
6) Sheath
Installation
Install the fuel shut-off valve on the fuel supply pipe between the filter and the burner, in the direction shown by the arrow cast
into the valve body. The valve's heat-sensitive element “must be immersed in the outward flow of hot water, close to or at the
top of the boiler, or in the outlet pipe within 1m of the boiler, upstream of any shut-off device” (R.2.A.4.2) (Fig.1). Weld the sheath
sleeve so that the sheath is immersed as fully as possible in the hot water, in one of the positions specified above. Depending
on the diameter of the pipe, the sleeve can be welded perpendicular or at an inclined angle in relation to the pipe (Fig.2) or on
a bend where possible (Fig.3).
Chart
Flow rate - pressure drop
Fig.2Fig.1
Fig.3
3
Fitting
To fit the NVFN Series fuel shut-off valve, proceed as follows:
1. Screw the sheath of the heat-sensitive element onto the sleeve;
2. Insert the bulb of the heat-sensitive element fully into the sheath;
3. Connect the valve to the burner supply pipe in accordance with the direction of flow shown on the valve body;
4. Carefully unroll the copper capillary, making sure that it is not resting on hot parts or the boiler
doors;
5. Push the plastic protective bushing on the end of the capillary into the sheath, then tighten the screw on the hexagonal
head of the sheath.
N.B. You can turn the control device on the cap through 360° to make it easier to fit the valve and lay out the capillary.
Resetting the valve
To reset the valve, proceed as follows:
A) Release the black protective cap;
B) Pull the green reset knob up;
A) Re-engage the black protective cap.
A C
B
To make sure the valve is open, check that the green reset knob appears in the top inspection window on the protective cap.
Overall dimensions (mm)
DN L H H1
1/2” 70 155 138
3/4” 70 163 141
1” 90 196 169
1.1/4” 150 204 169
1.1/2” 150 204 169
2” 170 222 179
5
H
H1
D
D
L
1/2”
DN L H H1
0
65 260 310 200
0
0
80 310 351 234
52,5
5
0
0
0
H1
H
D
L
D
52,5
1/2”
Specification text
NVFN Series
Liquid and gas fuel shut-off valve FLAMSTOP NVFN Series – WATTS brand. Positive action with manual resetting. Liquid
expansion thermostat. Capillary length 5m. Compact sensor. Aluminium body, stainless steel springs. NBR seals (FPM on
1/2” and 3/4” versions). 1/2”M sensor sheath connection (with 1/2”F x 3/4”M nipple). Setpoint temperature 97°C±3°C. Max.
operating pressure: 6 bar (DN 15-25) - 1 bar (DN 32-80). Max. temperature, sensor side 120°C. Maximum temperature, valve
side 50°C. 1/2” and 3/4” versions suitable for biodiesel. INAIL approved and set. Compliant with Directives PED 2014/68/EU
and ATEX 2014/34/EU.
Watts Industries reserves the right to carry out any technical and design improvements to its products without prior notice. Warranty: All sales and contracts for sale are expressly
conditioned on the buyer’s assent to Watts terms and conditions found on its website at www.wattsindustries.com. Watts hereby objects to any term, different from or additional to Watts
The descriptions and photographs contained in this product specification sheet are supplied by way of information only and are not binding.
terms, contained in any buyer communication in any form, unless agreed to in a writing signed by an officer of Watts.
NVFN-TS-IT-W-UK-11-18-Rev.2
Watts Industries Italia S.r.l.
Via Brenno, 21 • 20853 Biassono (MB) • Italy
Tel. +39 039 4986.1 • Fax +39 039 4986.222
infowattsitalia@wattswater.com • www.watts.com
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