Cooler−Bypass Thermostat Valve, Size 16
Q
max
= 300l/min,p
max
= 50bar
Temperature−controlled,integral relief function,choice of pressure settings
Series WDTUVA
1/4
Reference: 400−P−170101−E−01
Issue: 04.2010
S Temperature−dependent bypass control
S Integral pressure−relief function
S Oil warms up rapidly (cold−start phase)
S Direct−mounted in coolers or manifold blocks
S High flow rates
S Low headloss
S Choice of various pressure settings
S Very good reproducibility
S Extremely reliable
S Very stable operation
S All external parts zinc plated, chromited (CrVI−free)
S Can be fitted in a line−mounting body
1 Description
These direct acting bypass thermostat valves are size 16,
temperature controlled, high performance screw−in cartrid-
ges with an M33x1.5 mounting thread. They are intended to
be installed directly in coolers or line−mounting body. De-
pending on the temperature of the oil, they route the flow ei-
ther straight to tank or through the cooler. When the oil is
cold (<50°C), the connection P→T is open (bypass),
which means that the flow is directed to tank with minimal
headloss and the oil warms up rapidly. After the changeover
temperature is reached (>50°C), the integral thermostat
element closes the connection P→T. The valve now di-
rects the oil flow through the cooler. With an integral pres-
sure−relief function, the bypass thermostat cartridge also
safeguards the cooler by protecting it from any pressure
peaks that may result from excessive flow rates. The maxi-
mum pressure is determined by the model that is selected.
The cartridges are predominantly used in coolers in mobile
as well as industrial applications. All external parts of the
cartridge are zinc plated and chromited (CrVI−free) and are
thus suitable for use in the harshest operating environ-
ments.
2 Symbol
s
P
T
3 Technical data
General characteristics Description, value, unit
Designation cooler−bypass thermostat valve
Design temperature−controlled, integral relief function, choice of
maximum pressure setting
Mounting method screw−in cartridge M33x1.5
Tightening torque 60Nm ± 10%
Size size 16, cavity type KTU
Weight 0.65 kg
Mounting attitude unrestricted
Ambient temperature range −25°C +50°C
400−P−170101−E−01/04.2010
Series WDTUVA
2/4
Hydraulic characteristics Description, value, unit
Maximum operating pressure 50bar
Maximum flow rate 300l/min
Nominal pressure ranges 9bar, 6bar or 2bar (other pressures − consult BUCHER)
Temperature for start of control action 50°C
Flow direction see symbol
Hydraulic fluid HL and HLP mineral oil to DIN 51 524;
for other fluids, please consult BUCHER
Hydraulic fluid temperature range −25°C +80°C
Viscosity range 10650mm
2
/s (cSt), recommended 15...250mm
2
/s (cSt)
Minimum fluid cleanliness
Cleanliness class to ISO 4406:1999
class 20/18/15
4 Performance graphs measured with oil viscosity 33mm
2
/s (cSt)
Δp = f (Q) Pressure drop v. temperature [ 9bar ]
P0099.ai
0
2
4
6
8
10
T[°C]60 70 8050403020100
Q=20l/minQ=20l/min
p[bar]
Δp = f (Q) Pressure drop v. flow rate [ 9bar ]
P0100.ai
0
5
10
15
20
Q[l/min]300250200150100500
p[bar]
T=>60°CT=>60°C
T=<40°CT=<40°C
Δp = f (Q) Pressure drop v. temperature [ 6bar ]
P0108.ai
0
1
2
3
4
5
6
T[°C]
p[bar]
Q=20l/minQ=20l/min
60 70 8050403020100
Δp = f (Q) Pressure drop v. flow rate [ 6bar ]
P0110.ai
0
3
6
9
12
15
18
Q[l/min]300250200150100500
p[bar]
T=>60°CT=>60°C
T=<40°CT=<40°C
Δp = f (Q) Pressure drop v. temperature [ 2bar ]
P0109.ai
0
0.5
1
1.5
2
2.5
3
T[°C]
p [bar ]
Q=20l/minQ=20l/min
60 70 8050403020100
Δp = f (Q) Pressure drop v. flow rate [ 2bar ]
P0111.ai
0
2
4
6
8
Q[l/min]300250200150100500
p[bar]
T=>60°CT=>60°C
T=<40°CT=<40°C
400−P−170101−E−01/04.2010
Series WDTUVA
3/4
5 Dimensions & sectional view
Thermostat element (cold) ˘ connection P T open Thermostat element > 50°C ˘ P T closed
15
1)
52.550.25
107,5...117,5
0...8
1
M33x1.5
Ø 40
T
P
12
Ma = 60 [Nm] ± 10%
3
1)
10
P
T
Ma = 8 [Nm] ± 10%
IMPORTANT!
1)
The bypass thermostat valve can be closed
manually (locked) with the setscrew (A/F 3).
When this facility is not being used, make
sure that the screw is set to the dimension
15 mm ± 0.5.
Seals
Item Description
1 O−ring no. 028 ∅34,65x 1,78 N90
6 Installation information
IMPORTANT!
When fitting the cartridges, use the specified tigh-
tening torque. No adjustments are necessary,
since the cartridges are set in the factory.
ATTENTION!
Only qualified personnel with mechanical skills
may carry out any maintenance work. Generally,
the only work that should ever be undertaken is to
check, and possibly replace, the seals. When
changing seals, oil or grease the new seals tho-
roughly before fitting them.
400−P−170101−E−01/04.2010
Series WDTUVA
4/4
7 Application examples
Manifold block with integral cooler−bypass thermostat valve
V
2
V
1
WDTUVA ...
s
P
T
8 Ordering code
W = directional valve, cartridge construction
D = direct acting
T = temperature−actuated (thermostat element)
UV = pressure−relief function is incorporated
A ... Q = standard model − see relevant data sheets
Z ... R = special features − please consult BUCHER
50 = response temperature of thermostat < 50°C
= for other response temperatures, please consult BUCHER
90 = pressure setting = p
max
= 9bar
60 = pressure setting = p
max
= 6bar
20 = pressure setting = p
max
= 2bar
16 = size 16
(blank) = NBR (Nitrile) seals (standard)
V = FKM (Viton) seals
(special seals − please consult BUCHER)
1 ... 9 = design stage (omit when ordering new units)
−
Ex.
_
16ATD UV − 50 − 90 −W 1
9 Related data sheets
Reference (Old no.) Description
400−P−080141 Cavity type KTU
400−P−750151 Line−mounting body, type GEUA (G 1")
E 2010 by Bucher Hydraulics AG Frutigen, CH−3714 Frutigen
www.bucherhydraulics.cominfo.ch@bucherhydraulics.com
All rights reserved.
Data is provided for the purpose of product description only, and must not be construed as warranted characteristics in the legal sense.
The information does not relieve users from the duty of conducting their own evaluations and tests. Because the products are subject to
continual improvement, we reserve the right to amend the product specifications contained in this catalogue.
Classification: 430.300.−.305.330.380
