Acid and Caustic Neutralization Feed Calculator

Table of contents

• How to use
• Common mistakes
• Definitions
• Methodology
• Limitations & assumptions

Titratable demand: The measured acid or base amount needed to reach a chosen endpoint. It is a chemical quantity, unlike pH alone.

mg/L as CaCO3: Milligrams per liter reported as calcium carbonate equivalent. The titration method converts this value using the active reagent equivalent weight and the CaCO3 equivalent weight of 50 g/eq.

Active reagent equivalent weight (g/eq): Grams of active chemical that supply one equivalent of neutralizing capacity. It is used only with measured titratable demand.

Product strength by weight (percent): The percent of the delivered solution that is active chemical by mass.

Product density (lb/gal): The weight of one gallon of delivered solution. It converts solution weight into liquid feed volume.

Headroom: Extra pump capacity added above calculated peak chemical demand for a planning target.

gph: Gallons of delivered product per hour.

Mistake: Entering a pH value or pH change in Titratable demand to target (mg/L as CaCO3).
Fix: Enter a lab titration result to the intended endpoint, reported as mg/L as CaCO3. Use a documented dose if titration data are unavailable.

Mistake: Adding both Titratable demand to target (mg/L as CaCO3) and Tested active chemical dose (mg/L) as if they are combined.
Fix: Choose one dose method. The calculator uses only the dose input that matches How do you know the active chemical dose?.

Mistake: Using Product strength by weight (percent) where Product density (lb/gal) is needed.
Fix: Enter both supplier values separately. Strength converts active chemical to solution weight; density converts solution weight to gallons.

Mistake: Using Average flow (gpm) as Peak flow for pump sizing (gpm).
Fix: Use the highest expected operating flow for pump sizing, and keep it at least as large as average flow.

Mistake: Entering a pure-chemical price in Delivered product price ($/gal).
Fix: Enter the price of one gallon of the delivered solution. Leave it blank if no delivered-product quote is available.

Mistake: Treating Product volume for desired storage coverage as a final tank design.
Fix: Use it as the chemical volume for the selected days. Size the actual tank and containment under site, safety, delivery, and code requirements.

• The calculation needs measured titratable demand or a tested active dose. pH alone is not a valid chemical quantity basis for this tool.
• The titration method assumes the reported demand is at the target endpoint and that the entered active reagent equivalent weight is correct.
• Results use steady average flow for product use and cost. Rapid flow or water-quality changes can require a wider operating range, feed pacing, or control testing.
• Peak pump feed uses the entered peak flow and headroom only. It does not check pump turndown, pressure, suction conditions, calibration, injection point design, or chemical compatibility.
• Annual delivered chemical cost includes only delivered product volume times the entered price. It excludes equipment, installation, labor, controls, containment, mixing, and charges not included in the price.
• Storage quantity is chemical volume for the selected coverage days. It is not a final tank, freeboard, secondary-containment, delivery, or safety design.

Calculation method

The calculator first finds the active chemical dose. With measured titratable demand, it converts CaCO3-equivalent demand using the entered active reagent equivalent weight. With tested active chemical dose, it uses the entered dose directly.

active dose (mg/L) = titratable demand (mg/L as CaCO3) * active reagent equivalent weight (g/eq) / 50

It then converts stream flow to delivered product feed. Product strength is changed from percent to a fraction, and density converts pounds of solution to gallons.

average feed (gph) = active dose * average flow * 3.785411784 * 60 / 453592.37 / (strength / 100) / density

Daily product use equals average feed times operating time. Annual product use multiplies daily use by operating days per year. Annual cost appears only when a delivered-product price is entered.

annual product use (gal/year) = product use (gal/day) * operating days per year

annual chemical cost ($/year) = annual product use * delivered product price ($/gal)

Peak pump feed uses peak flow instead of average flow and then adds the entered pump headroom.

peak pump feed (gph) = base feed at peak flow * (1 + headroom / 100)

Worked example

For 100 gpm, 100 mg/L as CaCO3 demand, an equivalent weight of 40 g/eq, 50% product strength, and 10 lb/gal density, the active dose is 80 mg/L. The estimated average delivered feed is about 0.0802 gph. At 150 gpm peak flow with 25% headroom, the estimated pump feed is about 0.1503 gph.

Calculation details

The calculation uses 3.785411784 L per US gallon, 60 minutes per hour, and 453592.37 mg per pound. Average flow drives chemical use, while peak flow and headroom drive the separate pump-capacity estimate. Final feed settings should be confirmed with site testing and commissioning.