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COSHH Assessment — Hy-Ram Chlorine Disinfection Tablets

Ref Revision Issue Date Next Review Assessor Approved By
COSHH_07 2 1 June 2026 1 June 2027 Sean Ashton Aaron Mason, Director

Key references

COSHH_07 on the COSHH Register (APP_09)

Open Safety Data Sheet (PDF)

Sheet held: Chlorine Tablets, Merlin Chemicals, revision of 30/03/2015. Hy-Ram Engineering Ltd is the purchase supplier.

Download this COSHH as a Word document

Van-pack inclusion

This substance is carried in the field van packs. The Van Packs operative-facing site holds a synchronised copy.

1. Product identification
Product name Hy-Ram Chlorine Disinfection Tablets
Supplier Hy-Ram Engineering Ltd (sheet held: Merlin Chemicals)
Active ingredients / CAS Sodium dichloroisocyanurate (NaDCC)
CAS: 2893-78-9
Physical form Effervescent tablets
Appearance / odour White tablets, chlorine odour when dissolved
Use Disinfection of potable water mains following repair/installation

2. Hazard classification

Overall classification: Acute Toxicity (oral) Cat 4, Eye Irritation Cat 2, STOT SE 3 (respiratory), Aquatic Acute 1

Signal word: Warning

Hazard statements (H-codes)

Code Statement
H302 Harmful if swallowed.
H319 Causes serious eye irritation.
H335 May cause respiratory irritation.
H410 Very toxic to aquatic life with long lasting effects.
EUH031 Contact with acids liberates toxic gas.

Precautionary statements (key P-codes)

Code Statement
P261 Avoid breathing dust/fume/gas/mist/vapours/spray.
P264 Wash thoroughly after handling.
P271 Use only outdoors or in a well-ventilated area.
P273 Avoid release to the environment.
P280 Wear protective gloves/protective clothing/eye protection/face protection.
P301+312 IF SWALLOWED: Call a POISON CENTRE or doctor/physician if you feel unwell.
P305+351+338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
P501 Dispose of contents/container to an authorised waste contractor in accordance with local regulations.

GHS pictograms

Oxidising Explosive Flammable Toxic Harmful Corrosive Human Health Dangerous for environment Gas under pressure
☐ ☐ ☐ ☐ ☑ ☐ ☐ ☑ ☐

3. Persons at risk

Staff Public Visitors Contractor Workers Young / Pregnant
☑ ☐ ☐ ☑ ☑ ☐
  • Water-main operatives
  • Mains-commissioning personnel

4. Routes of exposure

  • Inhalation: Dust/fume may irritate respiratory tract
  • Skin contact: Irritation on prolonged contact
  • Eye contact: Causes irritation
  • Ingestion: Harmful if swallowed

5. Workplace exposure limits (HSE EH40/2005)

Component STD 8-hr TWA 15-min STEL Notes
Chlorine (released) — 0.5 ppm 1 ppm EH40/2005

6. Frequency and duration of exposure

COSHH Regulation 6 requires the assessment to consider the amount, level and duration of exposure.

Amount used Times per day Duration per use
Small — tablets 1–5 6–30 minutes

7. Control measures — hierarchy of controls

Elimination / substitution: Evaluated where practicable — see Section 12.

Engineering controls:

  • Dissolve only in approved chlorination rig
  • Never add water to tablet — add tablet to water

Administrative controls:

  • Use only for purpose specified
  • Keep away from acids
  • One tablet per intended volume only

Personal Protective Equipment (PPE):

  • Nitrile gloves
  • Chemical goggles
  • Dust mask when handling dry tablets

8. Storage and handling
Temperature Ambient, dry
Location Original container only. Locked cabinet.
Avoid Moisture, acids, ammonia, combustibles, direct sunlight
Container Original sealed drum — do not decant

9. Emergency procedures

First aid

Route Action
Eyes Rinse with water for 15 minutes. Seek medical advice.
Skin Wash with soap and water.
Inhalation Move to fresh air. Seek medical advice if symptoms persist.
Ingestion Rinse mouth. Drink water. Do NOT induce vomiting. Seek medical attention.

Spillage

Dry spill: sweep carefully (avoid dust) into container for disposal. Wet spill: dilute with large volumes of water. Do not return to container.

Fire

Not combustible but supports combustion. Use water spray. DO NOT use dry powder containing ammonium compounds.

Emergency contacts

  • Emergency services: 999
  • NHS non-emergency: 111
  • AMWS supervisor: Jason May
  • HSQE support: Sean Ashton (Onyx Operations)

10. Waste disposal

Hazardous waste. Dispose via authorised chemical-waste contractor.

11. Risk rating

Before controls With controls
High Low

Risk rating methodology: Severity × Likelihood = Risk (S × L = R). See POL_HSQE_21 — Risk Assessment for the full scoring matrix.

12. Training requirements

  • Water-main chlorination procedure
  • COSHH briefing
  • Spill response

13. Assessment outcome

Outcome
Safe to proceed with existing control measures ☑
Safe to proceed with additional actions ☐
Unsafe — do not proceed ☐

14. Monitoring and review

  • Weekly visual stock check
  • Expiry-date check monthly
  • Annual COSHH review

15. References

16. Signatures

Name Signature Date
Assessor Sean Ashton, HSQE Consultant 09/09/2026
Supervisor Jason May, Site Supervisor
Approved by Aaron Mason, Director
User acknowledgement

Reformatted 09/09/2026 to the 16-section COSHH template. Hazard classification, exposure limits, control measures and risk rating are unchanged from Issue 2 — the migration added the persons-at-risk grid, frequency and duration of exposure (COSHH Regulation 6), the GHS pictogram grid, the assessment outcome and the signature block.

This assessment must be reviewed annually or when circumstances change — whichever is sooner.

Method statements

The disinfection agent used on potable mains following repair or installation. MS 3.6 and MS 3.6.1 are the disinfection tasks; MS 3.12 and MS 3.11.2 are the repair and commissioning work that triggers them.

Ref Method statement
MS 3.6 Disinfection of Mains
MS 3.6.1 Super Chlorination of Water Mains
MS 3.11.2 Commissioning of Mains and Services
MS 3.12 Repair of Ductile Iron, PVC or HPPE Main

Held at Issue 2, 01/06/2026 on the Van Packs site and listed in APP_24. The method statement sets out the safe system of work for the task; this assessment controls the substance used within it.

This assessment is one of thirty held under APP_09. The substance-specific controls are above; the system that maintains them is below.

Standard applied: COSHH Regulations 2002 (undated reference), with workplace exposure limits taken from HSE EH40/2005 and hazard classification from GB CLP. Referenced undated so a new edition does not force a re-issue of every assessment.