Brochure

Legionella-Pneumophila risk
In systems producing domestic hot water with storage, in order to
avoid the dangerous infection known as Legionella , the hot water
must be stored at a temperature of at least 140°F. At this
temperature it is certain that the growth of the bacteria causing this
infection will be totally eliminated.
At this temperature, however, the water cannot be used directly.
As shown on the diagram opposite, temperatures of more than
120°F can cause burning very quickly. For example, at 130°F
partial burning will occurr in approximately 30 seconds, while at
140°F partial burning will occurr in approximately 5 seconds. The
time may be reduced by 50 percent or more for children and elderly
people.
In view of the above, it is necessary to install a thermostatic mixing
valve which can:
· reduce the temperature at the point of use to a value
lower than that of storage and suitable for sanitary users;
· maintain the temperature constant at the point of use
when the incoming pressure and temperature conditions
vary;
· have a thermal shut off function in the event of failure of
either hot or cold supply.
Thermal disinfection
The diagram shows the
behavior of the bacteria
Legionella Pneumophila
when the temperature
conditions of the water in
which it is contained
vary.
In order to ensure proper
thermal “disinfection”,
the values must not be
below 140°F.
Description of operation
A thermostatic mixing valve mixes hot and cold water in
such a way as to maintain constant set temperature of the
mixed water at the outlet.
A thermostatic element is fully immersed into the mixed
water. This element then contracts or expands causing
movement of the piston, closing either the hot or cold inlets,
regulating the flow rates entering the valve.
If there are variations of temperature or pressure at the
inlets, the internal element automatically reacts to restore
the original temperature setting.
Construction details
Anti-scale materials
The material used in the construction of the mixer eliminate
the problem of jamming caused by lime deposits. All the
working parts are made of a special anti-scale material,
with a low friction coefficient, guaranteeing that the
performance will be maintained over the long term.
Thermal shutoff
In the event of a failure of either the hot or cold supply, the
piston will shut off, stopping water discharging from the
mixed water outlet.
The Caleffi valve requires a minimum temperature differential
from hot inlet to mixed water outlet of 18°F (10°C) to ensure
the correct operation of the thermal shutoff function.
Temperature - Exposure time
110
120
130
140
150
160
170
∞F
0,1 1 10 100 1.000 10.000
Seconds
Partial burning
Total burning
Safety condition.
Maximum exposure
time at a given
temperature
COLD
HOT
MIXED
Exposure time for partial burns
Temperature Adult Children 0÷5 years
160°F 1 s --
150°F 2 s 0.5 s
140°F 5 s 1 s
130°F 30 s 10 s
120°F 5 min 2.5 min
sweat connections
version
32
60
80
100
120
140
160
Kills bacteria instantly
Kills 90% of bacteria in 2 minutes
Kills 90% of bacteria in 2 hours
Optimum temperature
for growth of bacteria
Surviving bacteria inactive