HTH^® Chip Dosers are available in two sizes, 35-kg and 180-kg.  These dosers are effective as a manual chlorination system or back-up chlorination system. 

Operating Procedures

The following calculation will determine the flow rate needed and eventually which doser should be used: 

C₁V₁ = C₂V₂

C₁ =             required chlorine residual level in final water (if chlorine demand is zero)

C₂ =             fixed theoretical maximum dissolve rate of HTH^® Scientific Chips

=             12 500 ppm (mg/ℓ)

V₁ =            volume of water to be treated (ℓ/hr)

V₂ =            Rotameter setting – water flow rate through doser (ℓ/hr)

For example if you have a 12 Mℓ/day capacity water plant and the final water specification for chlorine residual level is at least 1 mg/ℓ.  It was determined that the chlorine demand of the final water before chlorination was 4 mg/ℓ.   What is the needed flow rate setting on the rotameter? How much HTH^® Scientific Chips will be used in a month?

C₁ =             1 + 4 =  5 mg/ℓ

C₂ =             12 500 ppm (mg/ℓ)

V₁ =            (12 x 10⁶)/24 (ℓ/hr)

V₂ =             C₁V₁ / C₂

=             5 x 500 000 / 12 500

=            200 ℓ/hr flowrate (rotameter setting)

Now to determine operating costs:

M₁ = m₁ x 100/65 = V₁ x C₁

Where, M₁ = Weight of HTH^® Scientific Chips dissolved per hour

m₁ = 500 000 x 5 = 2 500 000 mg/hr

= 2.5 kg / hr

= 2.5 x 24 hr/day x 30 days/month

= 1 800 kg as 100% active chlorine

But HTH^® Scientific chips concentration is only min 65% active Chlorine

So you need to calculate the weight as:

M₁ = 1800 kg x 100/65 = 2770 kg of HTH^® Scientific Chips will be used on average per month.

IMPORTANT NOTICE:

HTH® Chip Doser only to be filled with HTH® SCIENTIFIC CHIPS.

Do not attempt to fill with HTH® Scientific Granular or any other product.

Wear appropriate PPE while filling the HTH® Chip Doser:

• Half-face dust/mist respirator
• Safety Boots
• Protective Gloves
• Protective overall or coat
• Safety goggles or full face shield

Technical Information

• 180kg Chip Doser (previously named 250-kg Chip Doser)

• Capacity  = 180kg HTH® Scientific Chips 
• Max feed rate = 50kg chips per hour  
• Flow rate = 40 – 4000 liter water per hour. Double rotameter system - 2000 liter maximum flow per rotameter 

• 35kg Chip Doser (recommended for WT facilities up to 1 Mℓ/day)

• Capacity  = 35kg HTH® Scientific Chips 
• Max feed rate = 10kg chips per day 
• Flow rate = up to 40 liter water per hour

Benefits

• Designed to suit harsh industrial and municipal conditions
• Simple effective dosage to virtually any size reservoir and/or WTW
• No handling of liquid chemicals
• Tailor made for every application need
• No electricity needed; gravity feed
• Low risk installation
• Easy, cost effective installation
• Continuous chemical dosing ensures safe drinking water
• The HTH® Chip Doser has proven reliability
• Dosage can be regulated with flow through rotameter

Installation and Operating Procedures

1. Complete risk assessment (Arch Technician)
2. Complete site survey (Arch Technician)
3. Customer to supply water supply point to doser (tap point)
4. Fit chip doser over selected manhole or selected channel (gravity feed)
5. Connect hose (½” OD) to the tap (water supply point) using a stainless steel clamp
6. Connect the other end of the hose to the rotameter inlet using a stainless steel clamp
7. Water flow through unit can be controlled with two valves; a) one on the tap (water supply point), and b) one on the rotameter
8. The rotameter is a ¾ fitting
9. Open the water supply valve to ensure water supply to the chip doser through the rotameter
10. Set required flow rate with valve on rotameter (as per calculation V₂)
11. Fill chip doser with HTH® Scientific Chips from the top of the doser (ensure to wear correct PPE as above)
12. Close chip doser lid tightly (clips could be connected to fasten and/or lock lid to chip doser)
13. Check Cl₂ ppm residual level in the water and open/close rotameter valve accordingly until desired Cl₂ residual level is reached.  Regular testing of this level should be done in order to achieve best quality water.
14. The chip doser should be cleaned when blockages occur at the bottom that results in no dosage or overflowing of chip doser from the top.

Cleaning Procedures: It is recommended to clean these chip dosers regularly from build-up to prevent blockages.  This cleaning procedure will form part of the training after installation by an Arch Technician.  For further details, please contact your nearest Arch Sales Engineer or Technician at 011 393 9000 (office) OR Rulani 0824987566 and Japie 0828677579.