Selection scope and sizing decision
Useful for: Fleet buyers and body engineers checking whether a requested water volume fits the selected chassis
For preliminary work, one cubic metre of water is commonly close to one tonne, but the project should state the density and temperature basis it uses. Final fill and water-quality rules can reduce usable volume.
Liquid position changes with tank geometry, baffles, grade and partial fill. The approved calculation must use the actual tank layout and load cases, not a centered point mass.
Sizing inputs
Supply these values before a model, body size or working rating is selected:
- 01Requested usable water volume
- 02Controlled water-density assumption
- 03Completed tank-system mass
- 04Chassis curb, gross and axle ratings
- 05Crew, fuel, hoses, tools and options
- 06Tank position, compartments and credible fill cases
From sizing inputs to model approval
Size from the operating requirement, test the complete configuration and retain the project records that control the final selection.
- 01Define the target duty
Water tanker volume and legal-payload calculation
- 02Quantify sizing inputs
Requested usable water volume; Controlled water-density assumption
- 03Test the complete vehicle
Water mass and Completed tare must both pass.
- 04Approve the selected rating
Controlled tank-volume definition; Water-density and operating allowance basis
Selection and sizing matrix
Use every row to test the proposed size. A nominal value is not sufficient when payload, geometry or operating limits conflict.
Scroll horizontally to view all columns.
| Decision factor | What to choose or check | Limit or condition |
|---|---|---|
| Water mass | Multiply usable volume by the approved density basis. | Liters are volume, not payload mass. |
| Completed tare | Include tank, subframe, equipment and every installed option. | Bare chassis curb mass cannot be subtracted directly from gross mass. |
| Axle reactions | Calculate each relevant loaded and partial-fill condition. | Passing gross mass does not prove axle compliance. |
| Usable fill | Apply venting, operating and water-service allowances. | Geometric shell volume is not automatically usable delivery volume. |
Applied calculation
Turn nominal water volume into a payload check Tank volume is translated into liquid mass before tare, crew, equipment, gross mass and axle limits are compared.
- 01Liquid mass12,000 kg
12 m³ × 1,000 kg/m³ - 02Loaded mass25,200 kg
13,200 + 12,000 - 03Approval gateBoth must pass
Loaded mass and each axle reaction ≤ approved limits
Decision: The illustrative loaded mass is 25,200 kg. Nominal tank volume is acceptable only if the selected chassis, completed tare and load distribution remain within every controlling limit.
Evidence boundary: Illustrative density and masses only. Use the actual liquid specification, weighed tare, controlled tank drawing and selected chassis limits.
Selection evidence checklist
Ask for evidence that is traceable to the selected model, configuration, vehicle or project scope. A record from another project is context, not verification.
- Controlled tank-volume definition
- Water-density and operating allowance basis
- Completed tare and equipment schedule
- Gross and axle-load calculation for approved load cases
Selection and sizing traps
Treating 10,000 L as a 10,000 kg payload line without context
Better selection method: State density, usable fill and all completed-vehicle masses.
Using chassis curb weight as finished tare
Better selection method: Add tank, subframe, pump, hoses, crew, fluids and options.
Checking only full load
Better selection method: Review credible partial-fill and axle-reaction cases required by the design.
Limitations
- This guide provides a preliminary calculation structure, not an engineering approval.
- The selected chassis, tank design and destination mass rules control final capacity.
- Reject or pause the configuration if tare, density, usable fill, axle reactions or legal limits are not controlled.
Evidence scope and technical basis
Each source is limited to what it can support. This makes the evidence chain readable to buyers, search engines and AI systems without turning a general source into a project claim.
Supports: Controls the project-input, quotation, approval and inspection workflow described in this guide.
Does not establish: It does not replace the signed quotation, approved specification, selected OEM documents or unit-linked project records.
Supports: Provides public checklists and worksheets; the signed project documents remain controlling.
Does not establish: It does not replace the signed quotation, approved specification, selected OEM documents or unit-linked project records.
Supports: Defines the relevant product family and published configuration boundaries. Project-specific ratings require the selected OEM documents.
Does not establish: It does not replace the signed quotation, approved specification, selected OEM documents or unit-linked project records.
Supports: Primary public guidance for tanker suitability, cleaning, hoses, delivery planning and potable-water controls. It does not approve a vehicle or replace local water rules.
Does not establish: It is authority, jurisdiction or subject specific and does not approve the selected vehicle for another destination or project.
Supports: Manufacturer example supporting tank, pump, PTO, valve and leak checks. Its component limits are model specific and not KEEYAK ratings.
Does not establish: It applies to the named manufacturer example and does not establish a KEEYAK model rating or project result.