Tenders

Project Name: [Insert Project Name]
Date: [Insert Date]
Version: 1.0
Client: [Insert Client Name]
Supplier: Hydrosight or equivalent

1. General Description

The underwater window shall be a prefabricated unit for permanent installation in concrete structures subject to water pressure. It must provide clear underwater visibility, structural integrity, and long-term waterproofing performance. Equivalent suppliers must demonstrate full compliance with this specification. Alternative proposals are permitted only if all performance criteria in this specification are demonstrably met.

2. Materials and Construction

The window systems are designed and built at the contractor’s facilities ready to be installed at site. Each unit is tested and certified to 1.5× of the design pressure before shipping.

  • Glazing
    • Monolithic cast acrylic (PMMA)
    • Fire Rating: DIN EN ISO 11925-2:2002-07
    • Optical transmittance: ~92%
    • Free from optical distortion. Must allow reading of 8pt Courier New text at 50 cm underwater
    • A certified engineer must submit an independent structural analysis. Stress limits: Water side: ≤3 MPa; air side: ≤5 MPa.(NOTE: This can be ommited and replaced by contractors recommendation if personal injuries as a result of material failture can be excluded from the use case)
  • Frame
    • Stainless steel EN 1.4404 (316L) or EN 1.4571
    • Fasteners: A4 or EN 1.4401
  • Sealant
    • Double-sealed
    • Shore A hardness ~45, elongation ~300%
    • Standards: EOTA ETAG 002, DIN EN ISO 7823-1, ASTM C1184

3. Environmental Compatibility

  • Water Types: Chlorinated ≤ 0.6 mg/l; ozone-enriched up to 200 pphm
  • pH Range: 7.0–7.4
  • Temperature
    • Operational: 5 °C to 30 °C (NOTE: Can be addapted to customers use case)
    • Material limits: –40 °C to +80 °C
    • For >15 °C differential between water and air sides, consult supplier

4. Waterproofing System

The system will integrate the window unit into the waterproofing layer of the tank. Preferably, all coating of the concrete will utilize the same material. The system must be:

  • Crack-bridging, mineral-based slurry (e.g. AQUAFIN-RS300)
  • Seamless, flexible, resistant to negative pressure (up to 2.0 bar)
  • DIN 4030 XA2 chemical resistance
  • Vapour permeable, frost/UV/ageing resistant
  • DIN 18195 Part 7 compliant
  • Compatible with tiles and wet duty classes A/B
  • Capable of watertight movement joints (e.g. ASO-Joint-Tape-2000/-S)

5. Installation

  • Client Responsibilities
    • Site Preparation
      • Concrete must be cured for at least 20 days
      • Surface must be clean, flat, and load-bearing
    • Environmental Conditions during Installation
      • Ambient temperature must remain between 5 °C and 25 °C
      • Dust, moisture, and direct sunlight must be controlled
      • No nearby work that generates vibration may occur
    • Access & Equipment
      • Tap water and 220 V electrical access
      • Compressed air supply (8 bar, NW 7.2 CEJN connection)
      • Crane access for units >100 kg
    • Safe working conditions, scaffolding, and protection from weather
  • Contractor Scope
    • Installation must follow the contractor’s technical documentation
    • Units must be anchored into prepared concrete openings
    • Waterproofing must be applied using mineral-based slurry
      • Minimum dry film thickness: 2.5 mm / 3.75 kg/m²
      • Application by brush, trowel, or spray with suitable equipment
    • 3 mm cover plates must be used to protect glazing during ongoing work

6. Contractor Requirements

  • ≥ 10 years in underwater window sector
  • Annual turnover in underwater window systems ≥ EUR 500,000
  • Insurance coverage ≥ EUR 2,500,000
  • Transport insurance
  • Documentation of experience and insurance must be provided

7. Warranty

  • Minimum 5-year warranty against leakage, delamination, and structural failure
  • Covers materials and workmanship