Walchem WebMaster ONE Instruction Manual page 15

Boilers:
The conductivity probe should be placed as close to the controller as possible, to a maximum
distance of 250 ft. The cable MUST be shielded from background electrical noise. Use 24 AWG,
3 twisted pair, shielded, low capacitance (15 pF/ft) cable such as Walchem P/N 102535 (Belden
9680) or equivalent.
Important Boiler Installation Notes: (see figure 1b and c)
1. Make sure the minimum water level in the boiler is at least 4-6 inches above the skimmer
blowdown line. If the skimmer line is closer to the surface, it is likely that steam will be drawn
into the line instead of boiler water. The skimmer line must also be installed above the highest
tube.
2. Maintain a 3/4 inch minimum pipe ID with no flow restrictions from the tap for the boiler
skimmer blowdown line to the electrode. If the ID is reduced below 3/4 inch, then flashing will
occur beyond that point and the conductivity reading will be low and erratic. Minimize the usage
of tees, valves, elbows or unions between the boiler and the electrode.
3. A manual shut off valve should be installed so that the electrode can be removed and cleaned.
This valve must be a full port valve in order to avoid a flow restriction. Keep the distance
between the tap for the boiler skimmer line to the electrode as short as possible, to a maximum
of 10 feet.
4. Mount the electrode in the side branch of a tee in a horizontal run of pipe. This will minimize
entrapment of steam around the electrode and will allow any solids to pass through.
5. There MUST be a flow restriction after the electrode and/or control valve in order to provide
back pressure. This flow restriction will be either a flow control valve or an orifice union. The
amount of the flow restriction will affect the blowdown rate as well, and should be sized
accordingly.
6. Install the motorized ball valve or solenoid valve per the manufacturer's instructions.
7. For best results, align the hole in the conductivity electrode such that the direction of water flow
is through the hole.
Guide to Sizing Blowdown Valves and Orifice Plates
1. Determine the Rate of Steam Production in Pounds per Hour:
Either read off the boiler name plate (water-tube boilers) or Calculate from horsepower rating (fire-tube
boilers):
HP x 34.5 = lbs/hr. Example: 100 HP = 3450 lbs/hr.
2. Determine the Concentration Ratio (BASED ON FEEDWATER)
A water treatment chemical specialist should determine the desired number of cycles of concentration.
This is the ratio of TDS in the boiler water to TDS in the feedwater. Note that feedwater means the water
that is fed to the boiler from the deaerator and includes makeup water plus condensate return.
Example: 10 cycles of concentration has been recommended
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