Quiz 10 : Belimo 250821

Pressure independent control valves (PICV) are often supplied by SCA but....

What exactly is "pressure independent"?

• Equal percentage flow characteristic at any operating pressure

• Maintain differential pressure across valve by manually adjust its shaft position

• Constant flowrate regardless of pressure fluctuation

• Able to operate & withstand any pressure condition

Main energy efficiency/saving features of PIFLV & PIQCV?

• Dynamic balancing

• Zero leakage (Ball valve design)

• Self cleaning (Ball valve design)

• Brushless motor

Common positioning / application of PIFLV & PIQCV?

• Fan coil unit

• Large AHU unit

• Chilled beams

• Heating/Cooling ceilings

Assume current PIFLV flow = 0.5 l/s..... If inlet pressure/flow increases to 0.8l/s

How will the flow limiting disc response to maintain chilled water flowrate?

• Remain unchanged due to pressure independent

• 1. Differential pressure across valve increases

  2. O-ring in disc begins to expand & restrict flow

  3. Flow reduces to set point

• 1. Differential pressure across valve increases

  2. O-ring start relaxing to allow more flow to pass through

  3. Flow returns to set point

• PIFLV will modulate by reducing its valve opening which lowers the flowrate & differential pressure

Assuming PIQCV is now operating at 0.25 l/s, differential pressure ( $\Delta P$ ) of 200 kPa.

How would pressure regulator & flowrate respond under scenario 1 & 2?

1 : Isolating valve before entering PIQCV is now turned half open
2 : Pump head increases (Higher inlet flow and pressure)

PIQCV still within working $\Delta P$ under these circumstances

• 1.  $\Delta P$ between P1 & P3 + pressure regulator position remained
  2.  $\Delta P$ between P1 & P3 $\uparrow$ , regulator opening & flow  $\downarrow$ 
  

• 1. P3 > P2; backflow occurs
  2. P1 > P3; regulator opening & flow  $\downarrow$
  

• 1. P1 > P2; regulator opening & flow  $\uparrow$
  2. P3 > P1; pressure regulator maintains its opening position
  

• 1.  $\Delta P$  between P1 & P3  $\downarrow$ , regulator opening & flow  $\uparrow$  
  2.  $\Delta P$  between P1 & P3  $\uparrow$ , regulator opening & flow  $\downarrow$  
  

Which of the following statements about PIQCV & PIFLV are "FALSE"?

• Behaves as pressure dependent valves whenever differential pressure is under or exceed its working range

• Both are equal percentage flow characteristic control

• Fouling/Clogging increases cooling coil consumption to cool down air which results in energy losses

• Vmax of PIQCV & PIFLV can be configured by using an end clip stopper

PIQCV comes with "PT port" option. Generally, they are used for ______

• Optimize pump performance
  

• Commission & troubleshoot systems
  

• Configure Vmax value of PIQCV
  

• Measure differential pressure and flowrate across the valve (Red port = $\uparrow$ kPa connection)
  

Site engineer gave you a call. He informed you that one of his operator had messed up the "end stop clip" position for C220QPT-D + CQ230A.

He is now asking where the clip has to be placed to set Vmax = 250 l/h

• "4 -"

• "6 +"

• "5+"

• "6 -"

C215QPT-D + CQK24A-SR

Based on the model above, what information can be gathered?

• 2-way valve, DN 15, Nominal flow = 0.11 l/s

  Fast running with electronic fail safe, AC/DC 24 V, Modulating Control

• 3-way valve, DN 15, Nominal flow = 0.58 l/s

  Spring fail safe, AC 24/230V, On/Off Control

• 2-way valve, DN 15, PT port option, Nominal flow = 0.27 l/s

  Non-spring, AC 24 V, Modulating Control

• 2-way valve, DN 15, PT port option, Nominal flow = 0.11 l/s

  Electronic fail safe, AC/DC 24 V, Modulating Control

In comparison, there are some difference between PIFLV and PIQCV.

Select the relevant points...

• PIQCV = on/off, 3-point & modulating control

  PIFLV limited to only On/Off control

• PIFLV does not requires end clip setting on actuator

• Both type have exact flowrate capacity and range of actuator models to pair with

• Both function with built-in pressure regulating mechanism & control valve under a single unit