Siemens QVE1901U Owner's manual

QVE1901U
Technical Instructions
Document No. 155-711
September 20, 2012
Flow Switch
Siemens Industry, Inc.
Description Flow switch for liquids in piping 3/4-inch to 8-inch (20 mm to 200 mm) diameter
Features •Contact load/switching capacity:
Maximum 24 Vac, 1 A, 26 VA
Maximum 24 Vdc, 1 A, 20 W
•Nominal pressure maximum 365 psi
•Manual setting of contact type (NO/NC)
•Housing IP 65 (excluding conduit adapter)
•Maintenance-free
Application The QVE1901U Flow Switch is used in HVAC installations to monitor the flow of fluids
in hydraulic systems, especially in refrigeration, heat pump and heating installations (for
example: for use with condensers, boilers, heat exchangers, and so on).
Product Number QVE1901U
Warning/Caution Notations
WARNING: Personal injury/loss of life may occur if you do not perform a
procedure as specified.
CAUTION: Equipment damage may occur if you do not perform a
procedure as specified.

Technical Instructions QVE1901U Flow Switch
Document Number 155-711
September 20, 2012
Page 2 Siemens Industry, Inc.
Mechanical Design The device records the flow of monitored
medium via a paddle system (1), which
has a permanent magnet (2) attached at its
upper end. A reed contact (3) is positioned
outside the flow above this magnet. A
second magnet (4) with opposite polarity is
used to create a reset force. The paddle
system moves once it comes into contact
with the monitored flow. The magnet (2)
changes its position to the reed contact (3).
The contact opens/closes depending on
the contact type. As soon as the flow is
interrupted, the paddle returns to its
original position and the reed contact
opens/closes depending on the contact
type.
(See Adjusting the Switching Unit.)
Reed Contact (3)
Paddle System (1)
Shaft
Flow
Magnet (4)
Magnet (2)
SEN0528R1
N
S
N S
Figure 1.
Switching Value Table
for Water at 68°F (20°C)
Make Contact (NO)
Red Arrow Break Contact (NC) White Arrow
1
2
V
SEN0529R1
1
2
V
SEN0530R1
1
2
V
SEN0530R1
1
2
V
SEN0529R1
Line
Size
Inches
(mm)
Max.
Flow
Rate
gpm
(m3/h)
Setpoints
gpm (m3/h)
Factory Setting
Setpoints
gpm (m3/h)
0.75
(19) 15
(4) 4.0 (0.9) 4.8 (1.1) 4.0 (0.9) 4.8 (1.1)
1.00
(25) 20
(5) 4.8 (1.1) 5.7 (1.3) 4.8 (1.1) 5.7 (1.3)
1.25
(32) 35
(8) 6.6 (1.5) 7.8 (1.8) 6.6 (1.5) 7.8 (1.8)
1.50
(40) 45
(10) 7.7 (1.7) 9.1 (2.0) 7.7 (1.7) 9.1 (2.0)
2.00
(50) 60
(14) 10.3 (2.3) 11.5 (2.6) 10.3 (2.3) 11.5 (2.6)
2.50
(65) 94
(23) 16.6 (3.8) 17.9 (4.1) 16.6 (3.8) 17.9 (4.1)
3.00
(80) 130
(30) 18.9 (4.3) 20.4 (4.6) 18.9 (4.3) 20.4 (4.6)
4.00
(100) 180
(40) 25.5 (5.8) 27.0 (6.1) 25.5 (5.8) 27.0 (6.1)
6.00
(150) 440
(100) 61.7 (14.0) 68.3 (15.5) 61.7 (14.0) 68.3 (15.5)
8.00
(200) 800
(180) 126.0(28.6) 130.4 (29.6) 126.0 (28.6) 130.4 (29.6)

QVE1901U Flow Switch Technical Instructions
Document Number 155-711
September 20, 2012
Siemens Industry, Inc. Page 3
Engineering Notes •On site:
– A T-junction with a female-threaded (1/2" NPT) fitting is required for 3/4” to 2”
line sizes.
– A 1-inch, female-threaded (1/2” NPT) welding socket is required for 3" to 8" line
sizes.
•All dimensions and data provided in the table of switching values are based on water
at 68°F (20°C), and the use of T-junctions and horizontal piping.
Flow Switch
Installation
•When choosing the installation site, ensure that the specified limit values (see
Technical Data) are not exceeded.
•Select suitable measures to prevent the medium from freezing. If the flow switch is to
be used in ambient temperatures of <39°F (4°C), do not carry out any operation
beforehand using pure water. Residual water in the flow switch can result in frost
damage.
Mechanical installation
General installation
instructions
•First, clean the pipe system where the flow switch is installed and remove any
magnetic particles, such as welding residue.
•The laminar path length in front of and behind the flow switch must be at least 10
times and 5 times the pipe diameter, respectively.
•The nominal installation position of the flow switch is an upright standing position in
horizontal pipework.
•The switches should only be installed in a vertical position with a maximum deviation
of 45°.
SEN0531R1
m
a
x
.
4
5
°
Figure 2. Acceptable Switch Mounting Positions.
•Ensure that there are no external magnetic fields in the immediate vicinity of the flow
switch, since these can impair device operation.
•There is an arrow on the flow switch. Install with the arrow parallel with the pipe
shaft, facing in the flow direction.
SEN0522R1
Figure 3. Flow Direction Arrow.
•The brass connecting nut G¾ has a tightening torque of 18 to 22 lb-ft (25-30 Nm)

Technical Instructions QVE1901U Flow Switch
Document Number 155-711
September 20, 2012
Page 4 Siemens Industry, Inc.
Line Size 3/4-inch to
8 inches
(20 mm to 200 mm)
Nut size 27
external thread
1/2-14 NPT
Welding adapter with
female 1/2-14 NPT,
adapter length 1’’
thread
3.15 - 0.79
(80) - (20)
SEN0533R1
40
30
20
15
9
50
60
70
80
Figure 4.
Installation Notes •Observe all local regulations from the electrical utilities or waterworks as applicable.
Electrical
Connections
WARNING:
Danger of death due to electrical voltage!
Always disconnect power to the system before connecting wires of the main
cable.
CAUTION: Destruction or damage of reed contact!
Note the maximum contact loads stated on the type plate.
The maximum contact loads stated on the type plate (switching voltage,
switching current, and switching capacity) refer to pure ohmic loads and may
not be exceeded under any circumstances.
High voltage and current peaks can occur, particularly when switching
inductive or capacitive loads (for example, relay coil, capacitors). Even a brief
overload can destroy (welding the contacts) or damage (reduced lifespan)
the reed contact.

QVE1901U Flow Switch Technical Instructions
Document Number 155-711
September 20, 2012
Siemens Industry, Inc. Page 5
Elbow Plug Connector
EN 175301-803-A
SEN0534R1
3
2
1
Lift
1 2 8
34
8
2
5
9
10
2
6
5
5
Figure 5. Figure 6. Figure 7. Figure 8.
•Loosen the central screw hM3×35 and disconnect the cable socket dfrom the
connector c. See Figure 5. Pull the central screw hout of the cable socket d.
•Open the core
jof the cable socket dwith a screwdriver or similar tool. See
Figure 6.
•Loosen the screwed conduit adapter gM16x1.5. See Figure 7.
•Insert the supply cable through the screwed conduit adapter g, the pressure ring
l, and the rubber insert kinto the cable socket d. See Figure 8.
•Connect the wires as shown in the connection diagram below.
SEN0535R1
Reed Contact
Reed Contact
Not Occupied
Not Occupied
Reed Contact
Not Occupied
Reed Contact
1
2
312
3
Figure 9.
•Press the core jinto the cable socket duntil it locks into place. See Figure 6
SEN0593R1
6
2
5
SEN0594R1
1
2
6
Figure 10. Figure 11.
•Put the central screw hin the cable socket d, and tighten the screwed conduit
adapter g. See Figure 10.
•Plug the cable socket don the connector cand retighten the central screw h.
See Figure 11.
•Ensure that all the connector seals e, f, and kat the plug connector have been
correctly inserted. See Figures 5 and 8.

Technical Instructions QVE1901U Flow Switch
Document Number 155-711
September 20, 2012
Page 6 Siemens Industry, Inc.
Adjust Switching
Unit
Standard Contact
The switching unit of the control switch enables two contact types:
1. Make contact (normally open): RED arrow on the switching unit
2. Break contact (normally closed): WHITE arrow on the switching unit
The following table explains the two contact types:
Contact Type Setting Flow Rate Electric
Contact
Increasing ClosingMake contact (NO) RED arrow Decreasing Opening
Increasing OpeningBreak contact (NC) WHITE arrow Decreasing Closing
The switching unit is factory set to make contact.
•To adjust the switching unit, open the cover of the switching head.
SEN0536R1
To Open Here
Figure 10.
•Loosen the locking screw (0.1” [2.5 mm] hexagon socket screw) and position the
switching unit until the red or white arrow is visible at the entry of the switching contact
guide to make contact or break contact, respectively.
•You can use the arrow length to make fine adjustments to the switching point:
Adjust to the arrowhead means: Switching point is at a lower flow rate.
Adjust to the arrow end means: Switching point is at a higher flow rate.
•Carefully retighten the locking screw.
•It is recommended that you use Loctite to secure the locking screw of the switching unit
after carrying out individual adjustments.
•Close the cover until it locks into place.
high flow rate
low flow rate
setting range
SEN0537R1
Make contact (Red Arrow)
Locking Screw
Red
White
high flow rate
low flow rate
setting range
Break contact (White Arrow)
Locking Screw
Red
White

QVE1901U Flow Switch Technical Instructions
Document Number 155-711
September 20, 2012
Siemens Industry, Inc. Page 7
Specifications
Functional data
Field of use
Suitable media water and water/glycol mixture
Piping diameter 3/4-inch to 8-inch (DN 20 to 200)
Type of switch Reed contact
Maximum contact voltage 24 Vac/ 24 Vdc
Maximum contact current 1A
Maximum switching capacity AC 26 VA/DC 20 W
Switching point adjustment Manual, supplied with minimum
switch-off value
Tolerance of switching
Point ranges in the table ±15%
Setting range See Switching Value Table
Medium temp. –4°F to 230°F (–20°C to 110°C)
(medium cannot freeze)
Nominal pressure Maximum 365 psi
Protective data Housing IP 65 per EN 60 529
Environmental
conditions General environmental conditions
Operation and storage –4°F to 176°F (–20°C to 80°C)
Ambient humidity <95% rh
Norms and standards conformity to Low-voltage directive 2006/95/EEC
Product standard EN 60204-1
Materials/color Housing Polyamide, black (non-wetted component)
Union nut Brass (non-wetted component)
Body Brass
Threaded adapter 1/2” NPT Brass
Paddle system PPO (Noryl GFN3), black
Axle Stainless Steel
Magnet Hard ferrite
Seal NBR
Weight Excluding packaging 10.93 ounces (0.31 kg)
Maintenance and repair The flow switch is maintenance-free and cannot be repaired by the user. In the unlikely
event of a defect, the device has to be returned to the manufacturer for repair.
Decommissioning and
disposal
SEN0540R1
•Never remove a flow switch or its upper parts from a system under pressure.
•Remove all the electrical connectors and disassemble the flow switch.
•The flow switch consists of various materials (see Specifications). Never dispose of the
level switch in domestic waste.

Technical Instructions QVE1901U Flow Switch
Document Number 155-711
September 20, 2012
Information in this publication is based on current specifications. The company reserves the right to make changes in specifications and models as
design improvements are introduced. Product or company names mentioned herein may be the trademarks of their respective owners.
© 2012 Siemens Industry, Inc.
Siemens Industry, Inc.
Building Technologies Division
1000 Deerfield Parkway
Buffalo Grove, IL 60089-4513
USA
[phone]
Your feedback is important to us. If you have
comments about this document, please send them
to SBT_technical.editor.[email protected]
Dimensions
Cutting the Paddle
Line Size
Inches
(mm)
L3 in. (mm)
0.75 (20) 1.69 ± 0.039 (43±1)
1.00 (25) 1.93 ± 0.039 (49±1)
1.25 (32) 2.13 ± 0.039 (54±1)
1.50 (40) 2.50 ± 0.039 (64±1)
2.00 (50) 2.91 ± 0.039 (74±1)
3.00 (80) 4.09 ± 0.039 (104±1)
4.00 (100) 4.49 ± 0.039 (114±1)
6.00 (150) 4.49 ± 0.039 (114±1)
8.00 (200) 4.49 ± 0.039 (114±1)
2.00 (50)
3.00 (80)
4.00 to 8.00 (100 to 200)
Line Size
0.75 (20)
1.00 (25)
1.25 (32)
1.50 (40)
SEN0538R1
Flow Switch
SEN0539R1
1.50
(38)
4.72
(120)
1.81
(46)
2.91
(74)
9
15
20
30
40
50
60
70
80
L3
0.78
(20)
1/2-14 NPT
3.42
±0,039
(87±1)
Dimensions in Inches (Millimeters).
Document No. 155-711
Printed in Germany
Page 8