Important Safety Instructions; Common Terms - Davey DPLGEU Mode D'emploi

2. IMPORTANT SAFETY INSTRUCTIONS

ATTENTION: Before carrying out any operation on the equipment, disconnect the power
supply. Any and all electrical work installing, servicing or decommissioning should be
handled by suitably qualified personnel.

3. COMMON TERMS

• Acid: A chemical compound that lowers pH by contributing hydrogen ions to a water solution.
• Acid dosing pump: Peristaltic pump to provide measured amounts of acid to the pool water to facilitate
pH correction by lowering pH.
• Alkaline (a.k.a. Base): A chemical that neutralises solids, usually by furnishing hydroxyl ions (OH-). The
opposite of an acid.
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• Balanced Water: The correct ratio of hardness, alkalinity, temperature, dissolved solids, and pH that
prevents pool water from being either corrosive or scale forming.
• Calcification: Formation of calcium carbonate scale on pool walls or the surface of circulation system
components due to the precipitation of calcium carbonate.
• Calcium Hardness: The calcium portion of the total hardness. The level of calcium determines whether
water is overly soft (too little) or hard (too much). Excessively high hardness levels may cause cloudy
water and scale. Excessively low levels may harm the pool.
• Calibration: The process of checking or adjusting (by comparison with a standard) the accuracy of a
measuring instrument.
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• Chlorine: A common oxidiser used as a disinfectant and algicide in swimming pools.
• Cyanuric Acid (C N O
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ultra-violet rays from sunlight.
• Hardness (water): Refers to the quantity of dissolved minerals, chiefly calcium and magnesium
compounds in the water. May be measured as Total Hardness (TH) or Calcium Hardness (CH). Not to be
confused with Total Dissolved Solids (TDS) which is different.
• Hydrochloric Acid (HCl) (a.k.a. Muriatic Acid): A strong acid used to reduce the pH and total alkalinity as
well to clean scale or acid wash surfaces. It is also generated in the reaction of chlorine gas and water.
• Hypochlorous Acid (HOCl): An unstable acid with excellent bactericidal and algicidal properties. The
active agent by which chlorine serves as a disinfectant. It is in dynamic equilibrium with hypochlorite ion
(OCl-), dependant on the pH of the water.
of 7.5. The correct pH in pool water is very important to ensure chlorine is able to disinfect efficiently.
• ORP (a.k.a. Oxidation Reduction Potential): A method of measuring the potential, which often relates to
the concentration of an oxidiser in the water.
available for use as an oxidiser. When measured by a probe the value should normally be 650mV but may
vary by ±15mV. Too high indicates too much chlorine while too low indicates chlorine levels are low.
• pH: A measure of the degree of acidity or alkalinity of a solution. A pH of below 7.0 is considered acid. A pH
above 7.0 is considered alkaline.
• Probe (a.k.a. Sensor or Electrode): A device placed in the pool water piping system that measures
specific water properties. The measurements provided are interpreted by the Davey Lifeguard controller to
either take corrective action or to initiate an alarm or warning that action is required.
• Re-climatising probes: the process of reinstating probes to their normal operating condition after being
allowed to dry out.
• Total Alkalinity: A measure of the ability of the water to maintain a desirable pH when acid is added
to the water.
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• Total Dissolved Solids: (a.k.a. TDS) refer to any minerals, salts, metals, cations or anions and some,
usually small amounts, of organic matter that are dissolved in water. Total dissolved solids (TDS) in a pool
commonly reflects the salt levels in the water. This can be measured with a conductivity probe.
• Total Hardness (TH): The total of all calcium hardness and magnesium hardness in water.
Ref: 1: National Swimming Pool Foundation Pool and Spa Operators Handbook 2017
H ) (a.k.a. Stabiliser): A chemical that restricts the loss of chlorine because of
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The equilibrium value where HOCl and OCl- are equal is at pH
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In swimming pools this is generally measuring the chlorine
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The pH of humans is between 7.35 and 7.45, i.e. slightly alkaline.
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