Danfoss DN 100 PCVQ Pilot Controlled Instruction Manual

: August 17, 2024
: Danfoss

Danfoss DN 100 PCVQ Pilot Controlled Instruction Manual

Safety Notes

To avoid injury of persons and damages to the device, it is absolutely necessary to carefully read and observe these Instructions.

Necessary assembly, start-up, and maintenance work may be performed only by qualified and authorized personnel.
Please comply with the instructions of the system manufacturer or system operator.

Definition of Application

The controller is used for flow rate limitation of water for heating, district heating and cooling systems.
The admissible medium temperatures depend on the design and comprise 5 to 140 °C, 5 to 150 °C, 5 to 200 °C.

The technical data on the rating plates determine the use.

Description

Construction

Mode of Operation

The control unit consists of the PCV-VFQ21 valve unit, installed in the main pipe and AVP-F installed as pilot controllers in the bypass. In the bypass line, a throttle element is installed in front of the pilot controller.
The controller keeps the differential pressure across the main valve flow restrictor on a constant level and restricts the flow rate to the adjusted setpoints.
The valve and the pilot valves are pressure- balanced.
The setpoint for the flow rate limitation is adjusted at the adjusting throttle of the valve unit.
The valve unit in the main pipe is opening on rising pressure. The pilot controller in the bypass line is closing on rising pressure.

Flow Rate Limitation

If the flow rate reaches the adjusted setpoint, the differential pressure increases at the adjusting throttle. This differential pressure acts on the actuator AVP-F via the impulse tubes and the valve AVP-F closes. Consequently, the valve of the valve unit is throttled, too, and the flow rate is restricted.

Technical Data

Technical data, see rating plates and the PCV data sheet.

Scope of Delivery

DN 100, DN 125

DN 150, DN 250

Assembly

Prior to Assembly:

Depressurized system before any assembly work !
CAUTION!

Clean pipeline system.
Install strainer in front of the controller.
Install shut-off units in front of and behind the controller.

Installation Position, Installation Place

Installation is only permitted in horizontal pipelines with the actuators hanging in a downward position.
The controller may be installed in the supply as well as in the return line.

When installing:

Observe direction of flow.
Design with welded ends:
Loads on the valve body and the throttle element by the pipes are not permitted.

Impulse Tube Installation

See installation scheme, section 6.6.
For CU pipes Ø 10 × 1, insert sockets 1 on both sides.

Care for correct position of the cutting rings 2 .

Insulation

The diaphragm actuators must not be insulated when insulating system parts.

Installation Scheme

Installation in the Return Line

Installation in the Supply Line

Assembly Drawings, Dimensions

DN 100 – DN 125

DN 150 – DN 250

Start-up

Required Static Pressure

The static pressure p1 in front of the controller must not fall below 1.5 bar (excess pressure). Non-observance may lead to cavitation and damages in the throttling element 1.

Leak and Pressure Tests

To avoid too high pressures at the diaphragm actuators, the following should be observed prior to any pressure tests:

Actuator of valve unit:
The admissible operating excess pressure in the actuator 2 is 25 bar¹ ). For higher pressures, you must:

Remove the impulse tubes 3 at the actuator and close the connections with a stopper.
Prior to any leak or pressure test, the instructions in section 7.3 must be complied with.

¹) Pre-condition: Same pressure on both sides of the diaphragm. If the pressure load is one-sided, the (+)diaphragm chamber may have an excess pressure of 1 bar in comparison to the (-)diaphragm chamber.

Filling the System

Note:
The controller 4 is closed when no pressure is applied and only opens with a defined flow in the bypass.
The pilot controller 5 is closing on rising pressure.

To avoid too high pressure differences on the controller, observe the following sequence when starting-up !

This procedure guarantees that there is no overturn of the diaphragm in the valve and the actuators.

Open units 6 of the system.
Slowly open shut-off units in the supply flow 7 and the return flow 8.

Start-up

During starting-up the filled system, open the units in the same sequence as described in section 7.3.

Putting out of operation

When putting the system out of operation, first close the shut-off units in the supply flow and then those of the return flow.

Flow Rate Adjustment

The setting of the setpoint for the flow rate limitation is made by means of flow adjusting curves (see section 7.7) or a heat meter (see page 33).

Adjustment by means of flow adjusting curves

Adjustment is to be made at a shut-down system.

Procedure

Unscrew cover 1.
Loosen the counter nut 2.

Screw.in the adjusting throttle 3 to its stop.

Choose diagram, (see section 7.7, Flow Adjusting Curves) Observe effecitve pressure Δpb: 0.2 or 0.5 bar see rating plate on the actuator AVP-F
Turn the adjusting throttle by this number of rotations to the left.
The adjusted flow rate can be verified by means of a flow rate measuring device. Perhaps you need to re-adjust the flow rate.
Care for an adequate differential pressure in the system.
Tighten the counter nut without changing the position of the adjusting throttle.
Re-screw the cap nut 1 .
The cap nut can be sealed.

The flow rate adjustment is completed. Now, adjust the differential pressure, see section 7.8.

Flow Adjusting Curves

Adjustment by means of a flow rate measuring device:

Procedure

Prior to the adjustment of the flow rate, start the system in accordance with the instructions given in section 7.4.
The shut-off units 1 and the control units 2 must be completely opened so that the flow rate is not restricted by a unit.
The adjustment can also be carried out via a bypass 3.
Unscrew cap nut 4.
Loosen the counter nut 5.
Adjust the flow rate limitation by turning the adjusting throttle 6 :
Turning to the right 7 , reduces the flow rate.

Turning to the left 8 , increases the flow rate.

Observe the flow rate indicator.
After having completed the adjustment, tighten the counter nut without changing the position of the adjusting throttle.
Re-screw the cap nut.
The cap nut can be sealed.

The flow rate adjustment is completed.

Sealing

The setpoint adjuster may be sealed.

Adjustment of the Throttle Valves

Number of throttle valves:
DN 100, 125: 1 ×
DN 150-250 : 2 ×

Unscrew cover 1.
Standard adjustment:
Turn in the valve spindle by turning it to the right by means of a wrench SW5 to its stop.
Then unscrew valve spindle by turning it to the left by approx. 10 rotations.
Increase of damping , e.g. necessary in case of pressure vibrations.
Screw in the valve spindle by turning it to the right.
Reduction of damping , e.g. in case of a control that is too slug.
Unscrew the valve spindle by turning it to the left.

Function Test

Flow rate

The adjusted flow rate must not be exceeded if the system is completely open.

If the setting is exceeded in either direction, check the adjustment as described in section 7.5.

Trouble Shooting

¹) The trim can be replaced by qualified personnel up to DN 125.
From DN 150 replacement should be carried out by the Danfoss service personnel.

Replacement of Valve, Actuator, Trims

Dismounting and Mounting Actuator and Valve

Note :
The springs 1 in the actuator are pre-stressed. Therefore, the actuator must be pushed upwards to be dismounted. You need a second person to do this.

Valve unit DN 100–125

Valve stem 3 and the stem of the actuator 4 are not screwed to eachother.

Dismounting

Dismount impulse tubes.
Support actuator below or by a second person as the springs 1 are pre-stressed.
Loosen union nut 2.
Remove actuator.

**Prior to assembly check cone 5 !

**

Clean cone prior to mounting.
Check O rings for damages, in case of damages, replace cone (see Spare Parts).
Grease cone with high-performance fitting component: BARRIERTA L55/3 HV (see Spare Parts).

Mounting

Place actuator at the valve and push upwards.
Screw on union nut 2.
Align actuator, observe position of impulse tube connections.
Tighten union nut 1 , max. torque 100 Nm.

Valve unit DN 150–250

The stem of the actuator 4 is screwed into the valve stem 3.

Dismounting

Dismount impulse tubes.
Completely loosen union nut 1.
The actuator hangs on the screwed-in stem 4.
The actuator weights approx. 20 kg. In addition, an internal spring package is pre-stressed. Secure against dropping down before unscrewing.
Screw the stem of the actuators 4 out of the valve stem 3 by turning the actuator to the left.

Mounting

Place actuator at the valve and push upward to press the spring package in the actuator together (second person necessary).
Carefully turn actuator to the right. By this, carefully screw in the stem of the actuator into the valve stem to its stop.
**Then, return the actuator by approx. 1 rotation (to the left)**
Align actuator, observe position of the control lines connections.
Tighten union nut 1, torque 100 Nm.