7
3.4 The Reagents
The indicator reagent reacts with any oxidant, generally chlorine, to
create a pink color which the instrument measures and compares with
a sample of water without reagents.
The buffer reagent is required to control the sample pH to bring the
sample to neutral.
The reagents are provided already hydrated and require little operator
preparation.
The indicator reagents are packaged a plastic box. Each 125 mL
indicator will require the addition and mixing of the DPD powder
contained in the small brown bottle. This activates the indicator
reagent. The indicator reagents should be changed out on a 90 day
basis even if they are not fully used.
The 500 ml buffer does not require any preparation and is good for
one year.
After one year all the reagents will have been consumed and
replacement reagent set will be required. This can be ordered through
agent Catalog No.09991. This set will include a new plastic box with
four sets of Indicator reagents plus one 500 mL bottle of Buffer.
3.5 The Reagent Cooler
A reagent cooler is provided for the 125 ml indicator reagent.
For proper operation power must be applied by the Purge Air Sentinel
controller to the cooling chamber temperature controller. Clean dry
compressed air must also be provided at pressures between 5.5 and 7
bar (80 to 101.5 PSI).
The cooling chamber temperature controller governs the solenoid
which controls air flow to the vortex cooling unit. The air flow is turned
on or off as required to maintain the indicating reagent temperature at
20-25˚C. This extends the life of the reagent up to 90 days.
To provide this extended reagent life, power to the cooling power
supply and air pressure must be supplied full time.
4.0 Installation and Commissioning
Prior to use for the first time, one of the reagents (the
indicator) will have to be mixed. Refer to section 11.2
Replacing or Installing the Reagents.
4.1 Mounting and Site Selection
The instrument is designed for wall mounting. Choose a location that is
easily accessible for operation and service and ensure that the Purge
Control lamp is about eye level. Consideration must be made for the
plumbing and electrical conduit connections. The overall mounting
dimensions of the instrument are shown in Figure 4.
Figure 4: Overall Mounting Dimensions of the Instrument
Be sure that the instrument be mounted as close as possible to the
sampling point to ensure a quick response time (within 2-3 meters
(6-10 ft) of the sampling point).
