MBT•Na Instructions

Here are detailed instructions for Sodium 2-Mercaptobenzothiazole (MBT•Na).

Overview

MBT•Na is the sodium salt of 2-Mercaptobenzothiazole (MBT). It is a highly effective corrosion inhibitor, primarily used to protect copper and copper alloys (brass, bronze) from corrosion in aqueous systems. It is also used as an industrial biocide.

Its key advantage is that it is water-soluble, unlike its parent compound (MBT), which makes it easy to dose and apply in water-based systems.

1. Primary Uses & Applications

Cooling Water Systems: The main application. It forms a thin, protective film on copper surfaces, preventing galvanic and electrolytic corrosion.

Closed Loop Systems: Used in heating and cooling systems to protect copper heat exchangers and components.

Metalworking Fluids: Acts as a corrosion inhibitor for copper in cutting oils and coolants.

Industrial Biocide: Effective against bacteria, fungi, and algae in water systems.

2. Instructions for Use

A. Dosing (Feed Rate)

Initial Dose (Passivation): To establish the protective film, a high initial "slug" dose is required.

Typical Concentration: 50 - 100 mg/L (ppm) of active product, circulated for 24-48 hours.

Maintenance Dose: Once the film is established, a much lower continuous feed is sufficient to maintain it.

Typical Concentration: 2 - 10 mg/L (ppm) of active product.

Dosing must be continuous. The protective film degrades over time and requires a constant, low level of inhibitor to repair itself.

Crucial: The exact dosage depends on:

System water volume and bleed-off rate.

Water chemistry (pH, temperature, hardness).

Severity of the corrosion problem.

Always consult the product's technical data sheet (TDS) for the supplier's specific recommendations.

B. Feeding Method

Continuous Feed: The preferred and most effective method. Use a chemical metering pump to inject a diluted solution of MBT•Na directly into the water stream (e.g., at the suction side of the system's circulating pump).

Intermittent Feed: Less effective but sometimes used. This involves adding a larger dose at regular intervals (e.g., daily). This can lead to fluctuations in protection levels.

C. Solution Preparation

MBT•Na is typically supplied as a liquid solution (e.g., 30-50% active) or a solid.

Dilute the product with clean, ambient temperature water to create a stock solution for feeding. A common dilution ratio is 1:10 (e.g., 1 part product to 10 parts water).

Mix thoroughly until homogeneous.

3. Important Precautions & Compatibility

pH Sensitivity: MBT•Na works best in a neutral to slightly alkaline pH range (7.0 - 9.5). In highly acidic conditions (pH < 6), it can convert back to its insoluble form (MBT), which will precipitate and become ineffective.

Oxidizing Biocides (Chlorine, Bromine):

MAJOR INCOMPATIBILITY. Oxidizing agents will rapidly degrade and destroy MBT•Na.

Do not feed MBT•Na simultaneously with chlorine or bromine-based biocides.

A feeding schedule must be established (e.g., feed biocide, allow residual to drop to zero, then feed corrosion inhibitor).

Metals: While excellent for copper, it is not effective for protecting ferrous metals (steel, iron) from corrosion. A multi-metal treatment program that includes a specific ferrous metal inhibitor (e.g., a phosphonate, silicate, or molybdate) is often required.

Environmental Toxicity: Like MBT, it is toxic to aquatic life. Do not allow concentrated product to enter drains or waterways. Disposal must comply with local environmental regulations.

4. Safety & Handling (GHS Pictograms)

Hazard Precaution

Causes serious eye irritation. Wear safety goggles or a face shield.

May cause skin irritation. Wear chemical-resistant gloves (e.g., nitrile) and protective clothing.

Harmful if swallowed. Do not eat, drink, or smoke when handling. Wash hands thoroughly after use.

Toxic to aquatic life. Prevent release to the environment.

Always refer to the Safety Data Sheet (SDS) provided by your supplier before handling or using this product.

Summary of Key Points

Use For: Protecting copper and brass from corrosion.

Initial Dose: 50-100 ppm for 1-2 days.

Maintenance Dose: 2-10 ppm continuously.

pH Range: Keep system pH between 7.0 - 9.5.

NEVER Mix With: Chlorine or bromine. Stagger the feed times.

Safety: Wear eye and skin protection. Consult the SDS.