Dosaodor-D
5
Product Description
The Dosaodor-D is a computerized system for natural gas
that injects odorant proportional to the flow rate of the gas
in transit. The system operates by liquid-injection and can
be installed in combination with traditional absorption-type
devices. The Dosaodor-D system is completely configurable
and can also be interfaced with remote monitoring systems.
The equipment consists of a pneumatic panel to be installed
in the hazardous area and a microprocessor electronic
control unit to be installed in the safe area, interconnected
by electric cables. The system ensures the dosing rate while
keeping the desired odorant concentration level steady with
over the entire flow range of the system, even when the
latter is extremely variable and extremely low. This particu-
lar feature guarantees high safety within the sphere of the
natural gas distribution for public use. In fact, by maintaining
a constant level of odorant concentration not matter what
the gas flow rate, any leakage of gas can clearly be identi
-
fied decreasing the possibility of accidents. In addition to
this, printed reports of the gas volumes, and the quantity of
odorant emitted, provides facility managers with the data
confirming the correct operation of their systems.
The benefits of this new system are as follows:
• Operational safety
• Reliability
• Low maintenance cost
• User friendly
The system does not involve the use of dosing pumps
or other complex devices for the measurement of odor-
ant flow rates. The system uses the differential pressure,
which is always present between the upstream and down-
stream sections of a reduction and metering gas station
(min. 1 bar / 14,5 psi), and an electrically controlled injection
unit that has been designed and certified in accordance to
international standards for electrical equipment in EEx areas
where there can be a risk of explosion. The Dosaodor-D
utilizes the high-pressure upstream gas as the pneumatic
driving fluid in order to inject the odorizing liquid in the down
-
stream pipelines, creating a gas driven pump. The pneumat-
ic panel is made of stainless steel, without a painted finish,
or screen printing as odorizing liquids are aggressive.
A procedure has been designed to perform the decontami-
nation of the entire injection circuit. Although the chances
are very slight, the need to intervene for system mainte-
nance may arise. A special sampler provides the measure-
ment of the liquid that has been injected and transfers the
data to the electronic control unit of any adjustments to be
made, ensuring a high level of reliability and overall preci-
sion of the system, which is self-monitoring. During the op-
eration of the two-injection devices version, one shut down
on a reserve for the other.
The software provides an exchange between the two, to en-
sure that the same device does not always remain idle. The
concentration ratio is ensured by a special microprocessor
electronic control unit which receives input, either a digital
volume signal from a flow computer/volumetric counter, or
from an analog signal 4-20 mA, that compares the concen-
tration level to be maintained, and processes the correct
electrical signal to be transmitted to the injection device.
The control unit supplies accurate voltage and current to
the various equipment units while containing the separation
barriers to comply with the directives applicable to intrinsic
safety system installations. It must be installed in the safe
area and the standard version operates with 230 V 50 Hz or
12 V dc. In the event of malfunctioning or power outages,
the control unit saves the programming data by means
of a buffer battery and sends out a signal to activate any
emergency devices (it normally restarts operation of the
absorption-type emergency system).
The Dosaodor-D system complies with UNI 9463 Italian
standards and with relevant European Directives. The fol-
lowing table illustrates the correlation between the type of
odorizing liquid used, the maximum odorizing liquid capacity
and the maximum flow rate of the gas to be odorized.
Table 1. Maximum Injection Rate and Maximum Gas Volume
Maximum injection rate
Maximum gas volume S
m
3
/h
Maximum gas volume MSCF/h
l/h
lbs/h
(at 6.75 lbs/gal)
40 mg/S
m
3
(THT)
10 mg/S
m
3
(Mercaptan)
10 mg/S
m
3
(Mercaptan)
0.5 lbs/MMSCF
(Mercaptan)
0.5
0.89
12,500
50,000
892
1.783
1
1.78
25,500
100,000
1.783
3.567
2
3.57
50,000
200,000
3.567
7.133
4
7.13
100,000
400,000
7.133
14.267
6
10.68
150,000
600,000
10.698
21.400
8
14.27
200,000
800,000
14.267
28.534
10
17.83
250,000
1,000,000
17.834
35.667
12
21.40
300,000
1,200,000
21.400
42.800
14
24.97
350,000
1,400,000
24.967
49.934
