Danfoss AFPQ 4 Differential Pressure Controller User Guide

: June 8, 2024
: Danfoss

Table of Contents

AFPQ 4 Differential Pressure Controller
Safety Notes
Definition of Application
Assembly
Impulse Tube Mounting
Impulse Tube Mounting to Supply Flow AFPQ
Putting out of Operation
Set-point Setting
Adjustment of Flow Rate Limitation
Adjustment with flow adjusting curves
References
Read User Manual Online (PDF format)
Download This Manual (PDF format)

Operating Guide
AFPQ (4) / VFQ 2(1) / 73696480
AFPQ (4) / VFQ 2(1) DN 15-250

Differential Pressure Controller AFPQ (4) / VFQ 2(1)
www.danfoss.com

AFPQ 4 Differential Pressure Controller

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 flow rate limitation and differential pressure control of water and water glycol mixtures for heating, district heating and cooling systems.
The technical data on the rating plates determine the use.

Scope of Delivery1
Accessory, for connection to flow supply and return flow

Assembly

Admissible Installation Positions2
DN 15-80 media temperatures up to 120 °C:
Can be installed in any position.
DN 100250 all temperatures and DN 15-80 media temperatures > 120 °C:
Installation only permitted in horizontal pipelines with the actuator hanging downwards.

Installation Location and Installation Scheme3
AFPQ/VFQ 2(1) return flow mounting AFPQ 4/VFQ 2(1) supply flow mounting

Valve Installation4

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

Valve and Actuator Mounting5

Place actuator at the valve.
Align actuator, observe position of impulse tube connection 1.
Tighten union nut Torque 100 Nm

Impulse Tube Mounting

Overview
3 Mounting of impulse tube set
4 Connection for copper impulse tubes

Procedure6

Remove plug 1 at the valve.
For AFPQ 4 remove plug in addition
Screw in threaded joint 3 with copper seal 5. Torque: 40 Nm
Verify the correct position of the cutting ring .
DN 150/250 screw angle 6 to the valve.
Screws angle to the pressure actuator.
7 AFPQ
AFPQ 4 **7** 1 Mount two angles.
For DN150-250, screw additional angle 2.
Press impulse tube 5 into the threaded joint up to its stop.
Tighten union nut 4 Torque 40 Nm

Impulse Tube Mounting to Supply Flow AFPQ

Return Flow AFPQ 4 **8**

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

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

Pipe

Stainless steel
DIN 17458, DIN 2391| Ø 10×0,8
Steel DIN 2391| Ø 10×1
Copper DIN 1754| Ø 10×1

Connection of impulse tube in the 3 system
Return flow mounting 4
Supply flow mounting 5
Connection to the pipeline9 1
No connection downwards 2, could become dirty.

Impulse Tube Mounting (Copper)

Cut pipe into rectangular sections 3 and burr.
Insert sleeves 4 on both sides.
Verify the correct position of the cutting ring 5.
Press impulse tube 6 into the threaded joint up to its stop.
Tighten union nut 7. Torque 40 Nm

Insulation10

For media temperatures up to 120 °C the pressure actuator 1 may also be insulated.

Dismounting11

Danger
Danger of injury by 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 Tests12
**Pressure must be increased slowly at the +/ connection 1 until the max testing pressure is reached.
Non-compliance may cause damages at the actuator or valve.
Max. test pressure [bar] with connected impulse tubes: 25 bar**
In case of higher test pressures, remove impulse tubes at the pipeline 2 and at the valve 3.
Close connections with plugs G ¼ ISO 228.
Observe nominal pressure 4 of the valve.

Max. test pressure is 1,5 x PN
Filling the System, First Start-up13

**** The return flow pressure 1 must not exceed the supply flow pressure 2.
Non-compliance may cause damages at the controller.

Open shut-off valve that is possibly available in the impulse tube.
Open valves in the system.
Slowly open shut-off devices in the supply flow.
Slowly open shut-off devices in the return flow.

Putting out of Operation

Slowly close shut-off devices in the supply flow.
Slowly close shut-off devices in the return flow.

Set-point Setting

First set the differential pressure 14 1.
Set-point range see rating plate 14 2.

Differential Pressure Setting15

Start system, see section “First Start-up” Completely open all shut-off devices in the system.
Set flow rate to about 50 % 1 & 2.
Adjustment
Observe pressure indicators 3.
Turning clockwise 4 increases the set-point (stressing the spring).
Turning counterclockwise 5 reduces the setpoint (un-stressing the spring).
The set-point adjuster 6 may be sealed.

Adjustment of Flow Rate Limitation

The flow rate is limited by adjusting the stroke of the adjusting throttle.
There are two options:

Adjustment with the flow adjusting curves, only DN 15-125 16 remove the cap 1
Untighten the counter nut 2
Turning clokwise, fully close the flow limiter 3
Turning counter clockwise, set the flow 4 limitation according to the table. Tighten the counter nut 5 Tighten the cap 6
Adjustment with heat meter, see step 2, **17**.
Untighten the counter nut 1 Increase maximum flow limitation 2
Decrease maximum flow limitation 3
Observe limited flow on the flow meter 4
Tighten the counter nut 5
Tighten the cap nut 6
Cap nut may be sealed 7

Adjustment with flow adjusting curves

The system must not be running!
When closing the adjusting throttle (step 3), the actuator could be damaged in case of high pressure differences.

Screw in adjusting throttle **15** 2 up to its stop.
→ Valve is closed, no flow.
Select flow adjusting curve (see **16**).
Unscrew adjusting throttle by this number of rotations **16** 3
The setting is completed, continue with step 2, **18** 5.

Note
The adjustment may be checked when the system is running by means of a heat meter, see next section.

Flow Adjusting Curves **17**
△Pb see rating plate **14** 3.

Setting range of flow rate V depending on the restrictor differential pressure △pb

Adjustment with Heat Meter18

Pre-condition:
The system must run. All units in the system or a bypass 1 must be completely open. For the max. flow rate, the pressure difference △p 2 at the control valve must be at least:

△Pmin = 2 × △Pb
See also section “Flow rate is too low”.

Observe heat meter indicator.
Turn to the left 3 increase the flow rate.
Turning to the right 4 reduces the flow rate.
When the adjustment is completed:
Tighten counter nut 5.
Place cap nut 6 and screw tight.
Torque about 50 Nm
Cup nut may be sealed 7

Flow rate is too low, what to do?

Remedy:

Verify adjustment, see section before.
Check differential pressure at the control valve.
| △pb|
---|---|---
△p| 0,2| (V/kvs)2
0,5

△pb restrictor Differential pressure [bar] (see rating plate)
V max. flow rate [m3/h] kvs [m3/h]

Dimensions, Weights18
Flanges: connection dimensions acc. too DIN 2501, seal form C

D anfoss A/S
Climate Solutions • climatesolutions.danfoss.com • +45 7488 2222 • E-Mail: climatesolutions@danfoss.com

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