CHEMetrics C-7540 Dissolved Oxygen Comparator

Name: CHEMetrics C-7540 Dissolved Oxygen Comparator | 0–40 ppb
Brand: CHEMetrics

Overview

The CHEMetrics C-7540 is a compact dissolved oxygen comparator designed for ultra-trace DO (0–40 ppb) in high-purity waters. Paired with CHEMets® ampoules (kit K-7540) using Rhodazine D™ chemistry, it delivers fast, repeatable ppb readings without a benchtop photometer—ideal for boiler feedwater, condensate, deaerator outlets, ultrapure/process water, and nitrogen-blanketed tanks where oxygen control prevents corrosion and efficiency loss.

Key Features & Specifications

• Measurement range: 0–40 ppb O₂ (visual color-match scale)

• Method: CHEMets® colorimetric, Rhodazine D™ for trace oxygen sensitivity

• Readout: direct ppb via stable comparator color blocks—no power required

• Use cases: power plants, refining/petrochem, desalination make-up, W/WW labs, aquaculture QA

• Form factor: rugged, lightweight, glare-resistant scale for field work

• Deliverable: comparator only; CHEMets ampoules/kits and accessories ordered separately

How It Works

A sealed CHEMets ampoule draws a fixed-volume sample and reacts with Rhodazine D to produce a pink/magenta color proportional to dissolved oxygen. Insert the developed ampoule into the C-7540 comparator, rotate to the closest color block, and read ppb O₂ directly. The sealed design minimizes air intrusion and handling error.

Applications

• Boiler/feedwater programs: verify scavenger dosing (sulfite/DEHA), target <10 ppb at economizer inlets

• Condensate & deaeration checks alongside online analyzers

• Process water/UPW loops in power, chemical, and pharma utilities

• Aquaculture & environmental spot checks where trace O₂ control matters

Operating Steps (Quick Guide)

Rinse clean glassware; avoid aeration (fill from bottom, overflow, cap immediately).
Snap the CHEMets ampoule per kit instructions; allow the specified development time.
Insert ampoule in the C-7540 and rotate to the closest color match.
Record the ppb O₂ reading, sample point, time, and operator initials.

Best Practices & QA

• Compare under consistent lighting; use a blank for colored/turbid samples.

• Keep sampling lines short; purge to remove stagnant water.

• Standardize daily checks (same glassware, timing, lighting) for trendable data.

• Store ampoules cool/dry; observe kit shelf-life and safety notes.

Compatibility & Ordering Notes

• C-7540 = comparator only (visual scale).

• Pair with CHEMets K-7540 (0–40 ppb); related ranges available per manufacturer.

• Optional: carry case, extra ampoules, sample vials, and SOP quick-card.

Why Seven Star LLC

We supply genuine CHEMetrics CHEMets® solutions, provide SOPs tailored to boiler-chemistry programs, and help integrate handheld checks with your online analyzer strategy. Need multi-site kits, storage guidance, or training notes? We’ll package it for your team.

Request a Quote for CHEMetrics C-7540 Dissolved Oxygen Comparator (0–40 ppb)

Request a quote—tell us your sample points (BFW, condensate, DA outlet), expected ppb range, and monthly test volume. We’ll ship the CHEMetrics C-7540 comparator with the right CHEMets kits and a quick SOP card so your team can start right away.

Technical Overview

Manufacturer: the C-7540 comparator is made by CHEMetrics (Midland, Virginia, USA, a brand of AquaPhoenix Scientific). It is part of the CHEMets® dissolved oxygen range and is not a Dräger product.

The C-7540 comparator is a visual colorimetric test device used to measure trace dissolved oxygen in water, most commonly for boiler and power-plant feedwater or condensate corrosion-control monitoring. The test uses a CHEMet ampoule reagent based on Rhodazine D chemistry: the sample reacts with the reagent to develop a pink color proportional to the dissolved oxygen concentration present, which the operator then visually matches against printed or molded color reference standards built into the comparator block.

The comparator covers a measurement range of 0 to 40 ppb dissolved oxygen, with graduated color reference points typically provided at 0, 5, 10, 15, 20, 25, 30, and 40 ppb, giving plant chemists a fast, low-cost, equipment-light method for spot-checking trace oxygen levels without requiring an electronic dissolved-oxygen analyzer. The comparator is normally supplied as part of a complete visual test kit including ampoule reagents, with refill ampoule sets available separately for ongoing repeat testing.

Parameter	Value
Part Number	C-7540
Product Type	Dissolved oxygen comparator (visual colorimetric)
Measurement Range	0–40 ppb O₂
Method	CHEMets® colorimetric, Rhodazine D™ chemistry
Ampoule Kit	K-7540
Power	No power required

Applications

Trace dissolved-oxygen testing at the ppb level is a standard water-treatment and steam-cycle chemistry check in power generation and industrial boiler operations, since even very low levels of dissolved oxygen in feedwater and condensate can accelerate corrosion of boiler tubes, condensers, and associated piping over time. This comparator method gives plant chemistry and operations teams a quick, field-deployable way to verify that deaeration and oxygen-scavenging chemical dosing are working correctly, without needing to send samples to a laboratory or maintain a calibrated electronic analyzer at every test point.

This type of visual comparator kit is commonly used alongside continuous online dissolved-oxygen analyzers as a periodic verification/cross-check method, or as the primary trace-oxygen testing method at smaller facilities where a full online analytical system is not justified.

Why Seven Star LLC

Seven Star LLC supplies water and steam-cycle testing equipment, including dissolved-oxygen comparator kits, to power generation and industrial process customers across Oman and the GCC. Our technical sales team will confirm the part number, matching CHEMets ampoule kit and current specification with the customer before finalizing any order for this item.

Request a Quote for CHEMetrics C-7540 Dissolved Oxygen Comparator (0–40 ppb)

Contact Seven Star LLC to discuss dissolved oxygen testing equipment for your boiler feedwater or condensate monitoring program across Oman and the GCC, and to confirm specification details for this CHEMetrics test kit.

Related Products

CHEMetrics is a specialized American manufacturer of water-analysis test kits, founded in 1971 and based in Midland, Virginia, USA. Its self-filling Vacu-vials® and CHEMets® ampoules contain pre-measured, vacuum-sealed reagents that draw in the sample when the tip is snapped, giving fast colorimetric results with visual comparators or portable photometers.The range covers dissolved oxygen down to ppb levels, chlorine, ammonia, COD, hydrazine, iron, copper, phosphate, sulfide and many other parameters. These kits are used for boiler feedwater and condensate control, cooling water, wastewater and environmental monitoring in power generation, oil & gas, petrochemical and desalination plants. Seven Star LLC supplies genuine CHEMetrics test kits, refills and comparators in Oman and the GCC, helping plant chemists keep routine water checks reliable and repeatable.

Browse CHEMetrics products by category: Liquid Analytical Accessories.

Frequently Asked Questions