Danfoss Pressure Reducer AFD/VFG(S) 2(1) Installation Guide

: October 27, 2023
: Danfoss

Danfoss Pressure Reducer AFD/VFG(S) 2(1)

$Pressure Reducer AFD/VFG$S$ 2$1$$

Figures

$Pressure Reducer AFD/VFG$S$ 2$1$ Installation and Operations$

Safety Notes

Prior to assembly and commissioning to avoid injury of persons and damages of the devices, it is absolutely necessary to carefully read and observe these instructions.

Necessary assembly, start-up, and maintenance work must be performed only by qualified, trained and authorized personnel.

Prior to assembly and maintenance work on the controller, the system must be:
– depressurized,
– cooled down,
– emptied and
– cleaned.
Please comply with the instructions of the system manufacturer or system operator.

Definition of Application

The controller is used for pressure reduction of steam, water and water glycol mixtures for heating, district heating and cooling systems. The technical data on the label plates determine the use.

Scope of Delivery ❶

– control valve VFG 2(1)/VFGS2
– extension piece ZF4 for DN < 150 if Tmax > 200 °C
– actuator AFD
– flow divider FD for steam noise reduction
– seal pot V1, V2 if T >

Mounting

_Only for VFGS 2 valves:
If ordered, install flow divider cage. _Read installation Instructions ❷ attached to the flow divider cage.

Admissible Installation Positions ❸

DN 15‑80 media temperatures up to 120 °C:
Can be installed in any position.
DN 100‑250 and DN 15‑80, media temperatures higher >120 °C and always at steam:
Installation only permitted in horizontal pipelines with the actuator hanging downwards.

Installation Scheme ❹

Note : The valve is open without pressure and is closing on rising pressure.

System must be protected behind the pressure reducer by a safety monitoring unit (SV, SÜV) ①.

Valve Installation ❺

Install strainer ❹ ② before the controller.
Rinse system prior to installing the valve.
Observe flow direction ③ on the valve body.
Flanges ④ in the pipeline must be in parallel position and sealing surfaces must be clean and without any damage.
. Install the valve.
Tighten screws crosswise in 3 steps up to the max. torque.

Valve Actuator Installation ❻

Only for valves VFGS2 DN 15‑125; T = 200‑350 °C: Install stem extension ZF4.
Read Installation Instructions attached to the stem extension ①.

Valves DN 150‑250

The actuator stem must be screwed into the valve stem.

Observe the Installation Instructions for the DN 150 – 250 valves ②

Place the actuator stem to the valve stem and screw together gently by hand until it stops. Rotate the nut simultaneously – makes it easier ③.
Unscrew for approximately one turn.
Tighten union nut ④
Torque 100 Nm

Valves DN 15‑125

Screw the actuator nut to the valve neck ③.
Align actuator, observe position of impulse tube connection ⑤.
Tighten union nut ④
Torque 100 Nm

Impulse Tube Installation ❼

Note : When installing seal pots ①, please observe the Installation Instructions for the seal pots.

Which impulse tubes to use?
Use the impulse tube set AF (1×) ②:
Order No.: 003G1391
or use the following pipes:

Stainless steel	Ø 10×0.8	DIN 17458

DIN 2391
Steel| Ø 10×1| DIN 2391
Copper| Ø 10×1| DIN 1754

The impulse tube ③ can be connected directly to the valve ④ or to the pipeline ⑤.

⑥ ventilation socket, do not connect impulse tube.

Connection to the valve ❽

Remove plug ① at the valve (return side).
Screw in threaded joint G 1/4 ② with copper
seal, Torque 40 Nm.
– or –

Connection to the Pipeline ❾ ④

No connection downwards/upwards ⑤, could bring dirt/air into an impulse tube.

Cut pipe in rectangular sections ⑥ and deburr.
For copper pipe: insert sockets ⑦ on both sides.
Verify the correct position of the cutting ring ⑧.
Press impulse tube ⑨ into the threaded joint up to its stop.
Tighten union nut ⑩ Torque 40 Nm.

Insulation ❿

For media temperatures up to 100 °C the pressure actuator ① may be insulated.

Dismounting ⓫

Danger
Danger of injury by steam, hot water!

Valve without actuator is open ①, seal ② is in the actuator.
Prior to dismounting, depressurize system!
Carry out dismounting in reverse order to mounting.

Leak and Pressure Tests ⓬

Observe max. permitted pressure, see below.

The pressure ② behind the valve must not exceed the pressure ① before the valve.
Non compliance may cause damages at the controller ③.

Prior the pressure tests, it is absolutely necessary to disconnect the impulse tube ④.
Close connections with a plug e.g. G 1/4 ISO 228.
Max. pressure [bar] with connected impulse tube

AFD cm2	32	80	160	250	630
bar	16

6

| 1.5| 0.5

Observe nominal pressure ⑤ of the valve.
Max. test pressure is 1.5 × PN.

Filling the System, First Start‑up ⓭

The pressure ② behind the valve must not exceed the pressure ① before the valve.

Non-compliance may cause damages at the controller ③.

Open shut-off units ④ at the impulse tube, if any.
Slowly open shut-off unit ⑤ (inlet).
Slowly open shut-off unit ⑥ (outlet).
Only for actuator 630 cm²:
Open ventilation screw ⑦ by about 2 turns.
As soon as water is penetrating, close screw.

Putting out of Operation ⓮

Slowly close shut-off units ① (inlet).
Slowly close shut-off units ② (outlet).

Setpoint Adjustment ⓯

Set-point range see rating plate ①.

Adjust flow rate at a fitting ② after the pressure reducer ③ to about 50 % of the max. flow rate ④.
Adjustment of the pressure behind the valve ⑤.
Turning to the right ⑥ increases the set-point (stressing the spring, tension spring)
Turning to the left ⑦ reduces the set-point (unstressing the spring)
The set-point adjuster ⑧ may be sealed.