Volume flow controller, constant and rectangular

Volume flow controller for constant volume flows (model VRRK) - Ref. no. 500 - 506

Index:

Advantages and design features
Volume flow against duct cross-section
Minimum static pressure difference at the controller
Versions
Table 1: Flow noise
Table 2: Correction values for calculation of the radiating noise of a duct with fitted volume flow controller
Price list
Specifications
Twin controller (up to 600 x 600 mm)
- Twin controlle: price list
- Twin controller: flow noise

Advantages and design features

Range of application: Volume flow controllers model VRRK are used to automatically regulate a required air flow in rectangular ducts. Their task is to maintain a default nominal value of the volume flow in a manner which is uniform, dependable and independent of pressure variations in the duct.

Operating principle: Constant volume flow controllers work with a smooth-running, asymmetrically angled plate, which guarantees sensitive response behaviour even in the case of low-volume flows.

Pressure, accuracy and scope of use: The controller operates reliably from a minimum pressure difference, which depends on the air velocity (see diagram 1), to a maximum pressure difference of 1000 Pa. The flow rate variation is usually within a tolerance of ± 10%. If the air velocity is below 4 m/s or the controller is installed horizontally, variations may well be higher than indicated. This will also apply if the air flow profile is not uniform or is distorted by bends, sharp edges, bottlenecks or dirt.

Temperature: The components of the controller are largely age-resistant and operate within a temperature range from -30°C up to 100°C. A special, heat resistant version for temperatures up to 250°C (briefly even 300°C) is available on request. For volume flow controllers with electric or pneumatic actuators, the operating temperatures of the actuators also have to be considered.

Construction: The control plate is supported by two PTFE bearings, which are maintenance-free and smooth-running. One, resp. two, pneumatic dampers prevent the control plate from vibrating and oscillating and guarantee sensitive response behaviour and precise control.

Installation: The precise balance of the control plate by a counterweight guarantees exact control no matter in which position the device is installed. An undisturbed air flow profile in front of the volume flow controller is recommended because a disturbance (e.g. asymmetrically incoming air flow, bottlenecks or sharp edges) can have adverse effects on the responsiveness and effectivity of the system.

Adjustment: The volume flow controllers are delivered either with any flow rate required by the customer or with a factory-preset reference flow rate. The flow rate can easily be set or reset in the range of the corresponding scale by the customer with an Allen key (2 mm). On request, the flow rate can also be set by an electric or a pneumatic actuator.

Dimensioning: Before dimensioning a duct system and choosing a particular volume flow controller, it has to be considered that the air velocity in the duct system should be between 3.0 m/s and 10 m/s. The duct just in front and just at the back of the volume flow controller should have the same dimensions (height and width) as the volume flow controller. As a reference value or benchmark, an average air velocity around 6.5 m/s is recommended.

Insulation: The volume flow controllers can be delivered with a 30 mm noise, resp. heat, insulation. Should the customer provide his own insulation, the adjusting device resp. the bracket for the electric or pneumatic actuator can be extended accordingly. In this case the insulation width has to be specified by the customer.

Installation note: According to DIN 1946 T2, provisions are to be made that the volume flow controller and the duct system are accessible for maintenance and adjustment.

Volume flow against duct cross-section

Example:

Given: Volume flow controller
          Model VRRK, Ref. no. 500
          Width 400 mm
          Height 200 mm
          (duct cross section 0.08 m2)

Which volume flow is possible?

Solution according to the chart on the left:
          V at 3 m/s = 865 m3/h
          V at 10 m/s = 2880 m3/h

Air velocity between 3 m/s und 10 m/s.

Ref. no. 500:
- Constant volume flow controller, self-regulating
- Factory-preset reference flow rate according to customer specification
- Manual setting of the flow rate by adjusting device
- Variable height and width, constant length (385 mm)
- Height between 150 mm to 300 mm
- Width between 150 mm to 600 mm
- H <= B <= 2H
- Connection: 4 holes – flange 30 mm

Minimum static pressure difference at the controller

Example:

Given: Volume flow controller
          Model VRRK, Ref. no. 500
          Width 250 mm
          Height 200 mm
          Volume flow 810 m3/h
          (= air velocity 4.5 m/s)

Minimum static pressure difference Dp in Pa?

Solution according to the chart on the left: Dp = 80 Pa

Versions:

Pneumatic actuation

Ref. no. 502:
- Similiar to Ref. no. 500, factory-preset reference flow rate with variable control by pneumatic actuation, activation by control pressure from 0.2 to 1.0 bar (max. pressure 1.3 bar)
- Motor type: LTG SMA 1 or equivalent (up to width 250 mm)
ROX or equivalent (width 251 mm or larger)

Electric actuation

Ref. no. 503:
- Similiar to Ref. no. 500, factory-preset, control by an electric actuator and two set values, operating voltage 230 V, 50 Hz.
- Controller with two set values without intermediate positions, activation by switches
- Motor type: Belimo LM 230 or equivalent (up to width 250 mm)
Belimo NM 230 or equivalent (width 251 mm or larger)

Ref. no. 504:
- Similiar to Ref. no. 503, additional auxiliary switch for activation of an additional switching command
- Motor type: Belimo LM 230 S or equivalent (up to width 250 mm)
Belimo NM 230 SN1 or equivalent (width 251 mm or larger)

Ref. no. 505:
- Similiar to Ref. no. 503, operating voltage 24 V, 50 Hz
- Motor type: Belimo LM 24 or equivalent (up to width 250 mm)
Belimo NM 24 or equivalent (width 251 mm or larger)

Ref. no. 506:
- Similiar to Ref. no. 503, variable control by electric adjustment , operating voltage 24 V, 50 Hz, activation by input signal between 2 and 10 V DC
- Motor type: Belimo LM 24 SR or equivalent (up to width 250 mm)
Belimo NM 24 SR or equivalent (width 251 mm or larger)

Table 1: Flow noise

Width in mm	Height in mm	Velocity in m/s	Volume flow in m³/h	Static pressure difference at the controller in Pa
				100 Pa								Summation Lw sum A-weighted in dB(A)	250 Pa								Summation Lw sum A-weighted in dB(A)	500 Pa								Summation Lw sum A-weighted in dB(A)
				Octave power level* L_w in dB/octave									Octave power level* L_w in dB/octave									Octave power level* L_w in dB/octave
				63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz		63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz		63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz

150	150	3	243	49	48	47	45	43	41	39	36	49	57	56	55	53	51	49	47	44	57	63	62	61	59	57	55	53	50	63
		6	486	54	54	52	51	49	48	45	43	55	62	61	60	59	57	55	53	51	63	68	67	66	65	63	62	59	57	69
		9	729	57	56	56	54	53	51	49	47	58	65	64	63	62	61	59	57	55	66	71	70	69	68	67	65	63	61	72
300	150	3	486	52	50	49	47	45	43	40	37	50	60	58	57	55	53	51	48	45	58	66	64	63	61	59	57	54	51	64
		6	972	56	56	54	53	51	49	47	44	57	64	64	62	61	59	57	55	52	65	70	70	68	67	65	63	61	58	71
		9	1458	59	59	58	56	55	53	51	48	60	67	66	66	64	63	61	59	56	68	73	73	72	70	69	67	65	62	74
200	200	3	432	52	50	49	47	45	43	40	37	50	60	58	57	55	53	51	48	45	58	66	64	63	61	59	57	54	51	64
		6	864	56	56	54	53	51	49	47	44	57	64	64	62	61	59	57	55	52	65	70	70	68	67	65	63	61	58	71
		9	1296	59	59	58	56	55	53	51	48	60	67	66	66	64	63	61	59	56	68	73	73	72	70	69	67	65	62	74
300	200	3	648	53	52	50	48	46	44	41	38	51	61	60	58	56	54	52	49	46	59	67	66	64	62	60	58	55	52	65
		6	1296	58	57	56	54	52	50	48	45	58	66	65	64	62	60	58	56	53	66	72	71	70	68	66	64	62	59	72
		9	1944	61	60	59	57	56	54	52	49	61	69	68	67	65	64	62	59	57	69	75	74	73	71	70	68	65	63	75
400	200	3	864	54	52	51	49	47	44	41	38	52	62	60	59	57	55	52	49	46	60	68	66	65	63	61	58	55	52	66
		6	1728	59	58	56	55	53	51	48	45	58	67	66	64	63	61	59	56	53	66	73	72	70	69	67	65	62	59	72
		9	2592	61	61	60	58	56	54	52	49	62	69	69	68	66	64	62	60	57	70	75	75	74	72	70	68	66	63	76
300	300	3	972	54	53	51	49	47	45	42	39	53	62	61	59	57	55	53	50	47	61	68	67	65	63	61	59	56	53	67
		6	1944	60	58	57	56	54	51	49	46	59	67	66	65	63	62	59	57	54	67	74	72	71	69	68	65	63	60	73
		9	2916	62	62	60	59	57	55	53	50	63	70	69	68	67	65	63	61	58	71	76	75	74	73	71	69	67	64	77
450	300	3	1458	56	54	53	50	48	46	43	39	54	64	62	60	58	56	53	51	47	62	70	68	67	64	62	59	57	53	68
		6	2916	61	60	58	57	55	52	50	47	60	69	68	66	65	63	60	58	55	68	75	74	72	71	69	66	64	61	74
		9	4374	64	63	62	60	58	56	54	51	64	72	71	70	68	66	64	62	59	72	78	77	76	74	72	70	68	65	78
600	300	3	1944	56	55	53	51	49	46	43	40	54	64	63	61	59	57	54	51	48	62	70	69	67	65	63	60	57	54	68
		6	3888	62	60	59	57	55	53	50	47	61	70	68	67	65	63	61	58	55	69	76	74	73	71	69	67	64	61	75
		9	5832	65	64	62	61	59	57	54	51	64	73	72	70	69	67	65	62	59	72	79	78	76	75	73	71	68	65	78

* Sound Level in dB/octave in relation to 10-12 W.

If air is blown into a room, additional attenuation occurs as a result of the duct outlet attenuation and room attenuation, thereby resulting in a reduction in the sound level.
The room and outlet attenuation can be calculated according to VDI 2081. As a rough estimate, approx. 8 dB can be deducted. To keep a required noise pressure level, it can be necessary to assemble a suitable sound attenuator between the volume flow controller and the room or to insulate the duct.
The flow noise is heavily dependent on local conditions, e.g. dimensions of the duct (height, width, length) behind the sound attenuator and the insulation of the duct. The specified data above, which have been acquired in the laboratory, can provide only a reference figure. The noise pressure level can rise if there is an additional noise source such as a ventilator or unfavorable air flow conditions. If this additional noise pressure level is smaller than the noise pressure level of the volume flow controller by approximately 10 dB, it will not cause an additive increase in that level.

Table 2: Correction values for calculation of the radiating noise of a duct (length: 6 m) with fitted volume flow controller

Width in mm	Height in mm	Duct without insulation								Summation A-weighted in dB (A)	Duct with 30 mm insulating shell								Summation A-weighted in dB (A)
		Correction value in dB / octave									Correction value in dB / octave
		63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz		63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz

150	150	0	2	2	3	4	6	7	8	4	0	4	6	11	14	17	17	17	12
300	150	0	4	5	6	8	9	11	11	7	0	6	9	14	18	20	21	20	14
200	200	0	2	2	3	4	6	7	8	4	0	4	6	11	14	17	17	17	11
300	200	0	4	5	6	8	9	11	11	7	0	6	9	14	18	20	21	20	14
400	200	0	4	5	6	8	9	11	11	7	0	6	9	14	18	20	21	20	13
300	300	0	3	4	5	6	8	9	11	6	0	5	8	13	16	19	19	20	13
450	300	0	4	4	6	7	9	10	12	7	0	6	8	14	17	20	20	21	13
600	300	0	4	4	6	7	9	10	12	6	0	6	8	14	17	20	20	21	12

Example: Calculation of the noise pressure level

	Noise pressure level in dB / octave								Summation A-weighted dB (A)
Frequency	63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz	Summation A-weighted dB (A)
Flow Noise L_W according to table 1	53	52	50	48	46	44	41	38	51
Correction value according to table 2	0	-6	-9	-14	-18	-20	-21	-20
Room attenuation	-4	-4	-4	-4	-4	-4	-4	-4
A-weighting	-26	-16	-9	-3	0	1	1	-1
Noise pressure level L_A A-weighted dB (A)	23	26	28	27	24	21	17	13	33

Example:

Given: Volume flow controller
          Model VRRK, Ref. no. 500
          with 30 mm insulating shell
          Width 300 mm
          Height 200 mm
          Volume flow 648 m3/h
          (= velocity 3 m/s)
Static pressure difference ∆p 100 Pa

Noise pressure level of a duct (length: 6 m) with integrated volume flow controller?

Calculated noise pressure level: 33 dB(A)

Example: Calculation of the flow noise

	Noise pressure level in dB / octave								Summation A-weighted dB (A)
Frequency	63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz	Summation A-weighted dB (A)
Flow noise L_W according to table 1	53	52	50	48	46	44	41	38	51
Reflection attenuation	-18	-10	-5	-1	0	0	0	0
Room attenuation	-4	-4	-4	-4	-4	-4	-4	-4
A-weighting	-26	-16	-9	-3	0	1	1	-1
Noise pressure level L_A A-weighted in dB (A)	5	22	32	40	42	41	38	33	46

Example:

Given: Volume flow controller
          Model VRRK, Ref. no. 500
          Width 300 mm
          Height 200 mm
          Volume flow 648 m3/h
          (= velocity 3 m/s)
          Static pressure difference p 100 Pa

Flow noise of a duct (length: 6 m) with integrated volume flow controller?

Calculated noise pressure level: 46 dB(A)

Constant volume flow controller (model VRRK): Price list

Nominal width W mm	Nominal height H mm	Length L mm	Ref. No. 500 Price €	Additional charge for PUR-coating €	Additional charge for insulating shell €
150 - 300	150 - 200	385	181.-	86.-	158.-
301 - 400	150 - 200	385	194.-	94.-	158.-
200 - 350	201 - 250	385	198.-	102.-	189.-
351 - 500	201 - 250	385	206.-	110.-	189.-
250 - 400	251 - 300	385	209.-	117.-	189.-
401 - 500	251 - 300	385	217.-	123.-	189.-
501 - 600	251 - 300	385	219.-	129.-	197.-

Because of aerodynamic conditions and for reasons of stability. the width should be at a maximum twice the height; the width must not be smaller than the height (H <= W <= 2H).

Prices for Ref. no. 502 – 506 on request.

Specifications

Manufacturer: AEROTECHNIK E. Siegwart
Model: VRRK, Ref. no. 500

Constant volume flow controller, mechanical, self-regulating, rectangular, flange C30, flow rate factory-preset, manual setting of the flow rate by the customer via a scale, high accuracy of volume flow, smooth-running and airtightly installed control plate, range of static pressure difference 50 Pa to 1000 Pa, range of volume flow 3:1, range of temperature –20°C to 100°C, ageing-resistant, maintenance-free, precise control in any installation situation.

Housing made of galvanized steel, control plate and vibration damper made of aluminium, bearings made of Teflon (PTFE).

Tolerance and leakage according to DIN 24190 and DIN 24194.

Twin controller

VRRK Ref.no.: 500 (Twin controller)

· rectangular, self regulating

· flow rate factory-preset, manual setting of the flow rate by the customer via a scale

· made of galvanized steel or of stainless steel

All Twin controllers are equipped with two control plates each with their own adjustment device with flow rate scale. The summation of both of the scale values results in the total volume flow rate.

Twin controllers cannot be delivered with electric or pneumatic actuation.

Twin controller: price list

Nominal Width W mm	Nominal Height H mm	Length L mm	Ref. No. 500 Price €	Additional Charge for PUR-Coating €	Additional Charge for Insulating Shell €
400	400	385	345	188	189
500	400	385	365	220	197
600	400	385	368	240	211
500	500	425	372	240	211
600	500	425	380	262	226
600	600	470	390	265	240

Flow noise

Width in mm	Height in mm	Velocity in m/s	Volume Flow in m³/h	Static Pressure Difference at the Controller in Pa
				100 Pa								Summation Lwtotal A-eval. in dB(A)	250 Pa								Summation Lwtotal A-eval. in dB(A)	500 Pa								Summation Lwtotal A-eval. in dB(A)
				Octave Power Level* L_w in dB/Octave									Octave Power Level* L_w in dB/Octave									Octave Power Level* L_w in dB/Octave
				63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz		63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz		63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz

400	400	3	1728	56	55	53	51	49	46	43	40	54	64	63	61	59	57	54	51	48	62	70	69	67	65	63	60	57	54	68
		6	3456	62	60	59	57	55	53	50	47	61	70	68	67	65	63	61	58	55	69	76	74	73	71	69	67	64	61	75
		9	5184	-	-	-	-	-	-	-	-	-	73	72	70	69	67	65	62	59	72	79	78	76	75	73	71	68	65	78
500	400	3	2160	57	56	54	52	49	46	43	40	55	65	64	62	60	57	54	51	48	63	71	70	68	66	63	60	57	54	69
		6	4320	62	61	60	58	56	53	51	48	61	70	69	68	66	64	61	59	56	69	76	75	74	72	70	67	65	62	75
		9	6480	-	-	-	-	-	-	-	-	-	73	72	71	69	67	65	63	60	73	79	78	77	75	73	71	69	66	79
600	400	3	2592	58	56	54	52	50	47	44	41	55	66	64	62	60	58	55	52	48	63	72	70	68	66	64	61	58	54	69
		6	5184	63	62	60	58	56	54	51	48	62	71	70	68	66	64	62	59	56	69	77	76	74	72	70	68	65	62	76
		9	7776	-	-	-	-	-	-	-	-	-	74	73	71	70	68	65	63	60	73	80	79	77	76	74	71	69	66	79
500	500	3	2700	58	56	54	52	50	47	44	41	55	66	64	62	60	58	55	52	49	63	72	70	68	66	64	61	58	55	69
		6	5400	63	62	60	59	56	54	51	48	62	71	70	68	66	64	62	59	56	70	77	76	74	73	70	68	65	62	76
		9	8100	-	-	-	-	-	-	-	-	-	74	73	72	70	68	66	63	60	73	80	79	78	76	74	72	69	66	79
600	500	3	3240	58	56	55	53	50	47	44	41	56	66	65	63	61	58	55	52	49	64	72	71	69	67	64	61	58	55	70
		6	6480	64	62	61	59	57	54	51	48	62	72	70	69	67	64	62	59	56	70	78	77	75	73	71	68	65	62	76
		9	9720	-	-	-	-	-	-	-	-	-	75	74	72	71	68	66	63	61	74	81	80	78	77	74	72	70	67	80
600	600	3	3888	59	57	55	53	51	48	45	41	56	67	65	63	61	59	56	53	49	64	73	71	69	67	65	62	59	55	70
		6	7776	65	63	62	60	57	55	52	49	63	72	71	69	68	65	62	60	57	71	78	77	76	74	71	69	66	63	77
		9	11664	-	-	-	-	-	-	-	-	-	75	74	73	71	69	67	64	61	74	82	80	79	77	75	73	70	67	80

* Sound Level in dB/Octave in Relation to 10-12 W

Table 2: Correction values for calculation of the radiating noise of a duct (length: 6 m) with fitted volume flow controller

Width in mm	Height in mm	Duct without Insulation								Duct with 30 mm Insulating Shell
		Correction Value in dB / Octave								Correction Value in dB / Octave
		63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz	63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz

400	400	0	3	4	5	6	8	9	11	0	5	8	13	16	19	19	20
500	400	0	4	4	6	7	9	10	10	0	6	8	14	17	20	20	19
600	400	0	4	4	6	7	9	10	10	0	6	8	14	17	20	20	19
500	500	0	4	4	6	7	9	10	10	0	6	8	14	17	20	20	19
600	500	0	4	4	6	7	9	10	10	0	6	8	14	17	20	20	19
600	600	0	4	4	6	7	9	10	10	0	6	8	14	17	20	20	19

Subject to alterations without advance notice