Resumo:
The water supply systems in Brazil present constant events of lack of supply, which
leads to the formation of air pockets in the network. At the moment the networks are
put into operation these air pockets are conducted to the distribution branches and end
up passing through the hydrometers. This causes the water meters to count air as
water, increasing the consumers' bills, which has led to lawsuits against the sewage
companies. This paper presents a survey of the efficiency of air eliminator equipment
designed to be installed in water supply trestles. Given the importance of the subject,
this paper seeks to analyze the efficiency of air elimination devices against bench tests
that aimed to reproduce situations of the device's operation in the field. These tests
contemplate pressures between 10 and 50 m.c.a., pressures that aim to reproduce the
maximum and minimum pressures of the supply network according to 12218 (ABNT,
2017a). For each pressure the devices were tested with flow rates of 0.18 m3
/h, 0.25
m3
/h, 0.50 m3
/h, 0.75 m3
/h, 1.00 m3
/h, 1.25 m3
/h, and 1.50 m3
/h, the operating
hypotheses considered were water supply, after emptying the network, and diluted air
in the runoff. The results obtained in the experiments with water return after a period
when the system was off-line showed performance values that are directly linked to
the pressure and flow requirements. Through data analysis it is possible to identify
pressure and flow ranges where the equipment presents its best performance and also
understand its behavior within other operation scenarios. The diluted air tests showed
that the analyzed equipment cannot eliminate the air and let the diluted bubbles pass
through the hydrometers. In all cases the air eliminators showed leaks under some
operating conditions.
