37-1-614 Page 21
pH Range at 25° C ......................................................... 6.5 – 8.0
Conductivity at 25°C (MICROMHO/cm) .........................
Less than 250
Total hardness as CaCo
3
(ppm) .....................................
Less than 100
Total Alkalinity as CaCo
3
(ppm)......................................
Less than 70
Chloride ion; CI
-
(ppm)....................................................
Less than 30
Sulfate ion SO
4
–2
(ppm) .................................................
Less than 50
Total iron; Fe (ppm) ........................................................ Less
than 0.3
Silica; SiO
2
(ppm) ...........................................................
Less than 20
Sulfide ion S
-2
(ppm).......................................................
0
Ammonium ion; NH
4
+ (ppm)...........................................
0
FIGURE 3-4 – WATER QUALITY REQUIREMENTS
If the injection water supply is allowed to run after blower shutdown, both the blower and adjacent
discharge piping may fill with water and present a serious overload problem at the next attempted start.
To prevent this, it is strongly recommended that an electric solenoid valve (normally open) be installed at
the lowest point in the discharge elbow and/or connecting piping. The valve will open on blower
shutdown and drain any water which might accumulate in the discharge piping. It is also recommended
that a time delay be used between injection water shutoff and blower/motor shutdown to allow the interior
of the blower to dry out prior to shutdown. Prior to shutdown, a dry out cycle of 5 minutes minimum with
no water injection is required while the blower is running under no load.
On wet vacuum service, temperature control and a minimum amount of rotor sealing is obtained with
small quantities (1 gallon per minute) of injected liquid. Best performance is attained by using the amount
of injected liquid that maintains the discharge air temperature in the range of 100
to 150
F.
The maximum permissible liquid rate on any size machine is shown in (FIGURE 3-3, page, 20). DO NOT
EXCEED THIS.
In applications where liquid carry--over from the upstream system may exceed these quantities, even for
momentary periods, separation prior to blower inlet must be employed to reduce water flow to this figure
or less.
Where inlet injection of water is used, it may be introduced in any convenient manner. No particular
water pressure is required, only that sufficient to deliver the water to the injection point. A reliable
metering device, such as a rotameter, to indicate water injection rate should be used.
Since water injection is used primarily for discharge temperature reduction and control, overheating will
occur with water shutoff or supply failure. Provisions against inadvertent water shutoff should be
incorporated in every water--injected blower system.
A high discharge temperature safety shutdown switch should be used to protect the blower.
Individual system requirements will determine whether downstream (discharge side) separation of
injection water may be required. Combination discharge silencers and separators are available.
See Engineering Data Sheet 37--1--432, for complete wet vacuum details.
