Hach 21055-69 DPD Free Chlorine Reagent Powder Pillows

Overview

The Hach 21055-69 is a pack of Hach DPD free chlorine reagent powder pillows, individually dosed chemical packets designed for use with Hach colorimeters and portable spectrophotometers to determine free chlorine concentration in the 0.02 to 2.00 mg/L Cl2 range. Each pillow contains a precisely measured, boric-acid-free DPD (N,N-diethyl-p-phenylenediamine) formulation that reacts with free chlorine to develop a pink colour proportional to concentration, giving water treatment operators a fast, repeatable field or laboratory test.

As the official authorized partner and exclusive regional representative for Hach in the Sultanate of Oman, Seven Star LLC proudly supplies the Hach 21055-69 reagent pillows with full manufacturer traceability and batch documentation. Water treatment plants and municipal laboratories across Muscat, Sohar, and Salalah rely on Seven Star LLC to source genuine Hach reagents quickly, avoiding the inconsistent colour development and failed compliance results that come with expired or counterfeit reagent stock.

Measurement Principle

The Hach 21055-69 reagent works on the DPD colorimetric principle: when the powder pillow is added to a 10 mL water sample, free chlorine present in the sample oxidizes the DPD indicator, producing a pink colour whose intensity is directly proportional to the free chlorine concentration. A Hach colorimeter or spectrophotometer then measures the light absorbance of the developed colour at the appropriate wavelength and converts the reading into a chlorine concentration in mg/L, following the USEPA-accepted Method 8021 for drinking water reporting.

Because each pillow is factory-dosed with an exact quantity of reagent, the method eliminates the weighing and mixing errors associated with bulk liquid reagents, and the boric-acid-free formulation avoids the buffer interference issues that affect some legacy DPD chemistries. The practical consequence for plant chemists is a test that is fast to execute, consistent from sample to sample, and directly defensible for regulatory reporting without additional calibration steps beyond routine colorimeter verification.

Engineering Design of the Hach 21055-69

The Hach 21055-69 is supplied as a pack of 100 individually sealed powder pillows, each containing a precisely measured 10 mL-sample dose of the DPD reagent blend. The foil pillow packaging protects the reagent from moisture and light degradation during storage and transport, preserving reagent activity through the stated shelf life so that results remain accurate even after extended storage in regional climate conditions.

The pillow format is designed for direct, tool-free use: the operator tears open the pillow and empties the contents directly into the sample cell, eliminating pipetting, dilution, or mixing equipment. This single-dose design also standardizes the test across multiple operators and shifts, since every pillow delivers an identical reagent quantity regardless of who performs the test, which is a meaningful quality-control advantage for utilities running continuous compliance monitoring programs.

Key Features

The Hach 21055-69 reagent combines regulatory-grade accuracy with field-ready simplicity, and the following features summarize why water utilities standardize on this chemistry:

• USEPA-accepted DPD method supports direct use in regulatory compliance reporting for drinking water analysis.
• Boric-acid-free formulation avoids buffer interference issues associated with some legacy chlorine reagent chemistries.
• Individually dosed powder pillows eliminate weighing, pipetting, and mixing errors in the field or laboratory.
• Foil packaging protects reagent activity from moisture and light across extended storage periods.
• Measurement range of 0.02 to 2.00 mg/L Cl2 covers typical drinking water and process water disinfection targets.
• Compatible with Hach colorimeters and portable spectrophotometers already deployed across most regional utility labs.
• Consistent single-dose format standardizes results across multiple operators and testing shifts.
• 100-pillow pack size supports high-frequency sampling programs without frequent reordering.

Industrial Applications

The Hach 21055-69 reagent is used throughout municipal water treatment plants, wastewater facilities, and industrial process water programs where free chlorine residual must be verified for disinfection efficacy and regulatory compliance. In Oman, the reagent is widely specified for RO desalination post-treatment disinfection verification, district cooling water treatment monitoring, and municipal drinking water distribution network sampling across urban and industrial zones.

As the officially authorized partner for Hach, Seven Star LLC distributes DPD reagent chemistry to utility laboratories and environmental consultants throughout the Sohar and Salalah economic zones, as well as to hospitality chains and hospital complexes across Muscat that maintain their own potable water and cooling tower chlorine monitoring programs. The reagent’s consistent, regulatory-defensible results make it a standard component of water quality testing kits across the GCC.

Technical Specifications

The table below summarizes the key parameters of the Hach 21055-69 DPD free chlorine reagent.

Call To Action

As the authorized partner for Hach in Oman and the GCC, Seven Star LLC supports formal RFQ submissions, holds regional warehouse stock for rapid dispatch, and can provide the full technical datasheet for the Hach 21055-69 reagent on request. Contact the Seven Star LLC instrumentation division for genuine Hach water quality reagents and application support across Muscat, Sohar, and Salalah.