Self-Draining Chemical Tanks
Self-draining chemical tanks with a sump-and-slope base that drains to zero. No residue, no dead zones, no contamination between runs.
23,000L, 28,000L and 33,000L, rated to 1.5SG, with custom fittings, telemetry and dosing integration on request.
DESIGNED FOR COMPLETE DRAINAGE
100% Self-Draining by Design
The tank base slopes to a centre outlet, which is connected to a channel exiting through the side wall. When the tank is opened, virtually no liquid remains on the bottom. The outlet drain sizes match downstream pipework and pump requirements, and the tank sits on a purpose-built base that maintains the drainage gradient without additional site-built support structures.
The design is engineered to hold liquids up to 1.5 specific gravity, covering the working density of most commercial and industrial chemicals in the market. For custom fittings, telemetry integration, or connection to Polymaster’s stand-alone dosing cabinet, the tank can be specified with all required nozzles and connections during manufacture.
POLYMASTER SELF-DRAINING TANK RANGE
Browse Our Range of Self-Draining Chemical Tanks
Three capacities, two material grades. Choose Hexathene Chem grade polyethylene for standard chemical storage or Hexathene Chem-Plus for aggressive chemicals including concentrated acids, hypochlorites, and caustics. All tanks share the same 3450mm diameter footprint.
| Code | Product | Capacity | Diameter (mm) | Height (mm) | ||
|---|---|---|---|---|---|---|
 | SDT23KL | 23,000L Self Draining Tank | 23,000L | 3450 | 3054 | Download Data Sheet Download Drawing Download STEP File |
 | SDT28KL | 28,000L Self Draining Tank | 28,000L | 3450 | 3601 | Download Data Sheet Download Drawing Download STEP File |
 | SDT33KL | 33,000L Self Draining Tank | 33,000L | 3450 | 4149 | Download Data Sheet Download Drawing Download STEP File |
23,000L Self Draining Tank
SDT23KL
28,000L Self Draining Tank
SDT28KL
33,000L Self Draining Tank
SDT33KL
Not sure which capacity or material grade fits your chemical? Our team can help you match the right tank to your specific chemical and site requirements. Call us on 1800 062 064 or use the enquiry form above.
Highest Quality and Standards
Every Polymaster self-draining tank is Australian-made, manufactured in chemical-grade polyethylene, and independently certified to the Australian standard for polyethylene chemical storage.
Australian Made
Designed, engineered, and manufactured in Australia by Polymaster since 1994.
Food-Grade Polyethylene
Food-grade polyethylene certified to AS/NZS 4020, the Australian standard for products in contact with drinking water.
ISO 9001 Quality Management
Polymaster holds ISO 9001 certification, the international standard for quality management systems.
AS/NZS 4766 Certified
Independently certified to AS/NZS 4766:2020 for polyethylene chemical storage tanks. Licence numbers BMP657671 and BMP650824.
WHERE POLYMASTER SELF-DRAINING TANKS ARE USED
Built for Australia’s Chemical Storage and Process Industries
Self-draining tanks are used wherever a process needs complete drainage between batches, chemical changes, or scheduled clean-outs. Polymaster’s range is deployed across water utilities, chemical manufacturing, mining, food and beverage, and transport operations throughout Australia.
Water and Wastewater Utilities
Municipal and industrial water treatment plants use self-draining tanks for coagulants, flocculants, disinfection chemicals, and pH adjustment chemistry where residual liquid must be cleared before restocking or a chemical change.
Chemical Manufacturers and Distributors
Chemical blenders, resellers, and industrial chemistry operators use the range for storage between batches, particularly for concentrated acids and bases where residue in a flat-bottom tank creates handling and compatibility risks.
Mining and Resources
On-site chemical storage at processing plants and mine sites uses the self-draining design for reagent storage, dosing supply, and chemical change-outs where full evacuation is required.
Food and Beverage
Processing facilities use self-draining tanks for sanitiser, CIP chemistry, and process water storage where flat-bottom residue would compromise the next batch.
Transport and Bulk Handling
Fleet fuelling depots, chemical transport operators, and tanker fill facilities use self-draining tanks for reliable full-load discharge to trucks and downstream equipment.
CHEMICAL COMPATIBILITY
Unmatched Chemical Compatibility
Every Polymaster chemical tank material is chemical-compatibility tested before it goes into service. Our specially formulated polyethylene resins safely contain a wide range of chemicals in commercial use, including:
- Sulphuric Acid (98%)
- Ferric Chloride
- Ferrous Chloride
- Nitric Acid
- Alum
- Sodium Metabisulphite
- Sodium Hypochlorite
- Sodium Hydroxide (Caustic)
- Hydrochloric Acid
- Magnesium Hydroxide
For chemicals not listed here, or for concentrations outside standard ranges, talk to a Polymaster polymer chemist to confirm material compatibility before ordering. A comprehensive chemical compatibility chart is available on request.
CUSTOM FITTINGS, TELEMETRY, AND DOSING
Custom Fittings, Telemetry, and Dosing System Integration
Self-draining tanks can be equipped with the full range of fittings and nozzles supplied on Polymaster’s chemical and process water tanks. If the standard configuration does not match your operation, the tank can be custom-designed with:
Custom Fittings and Nozzles
Inlet, outlet, overflow, drain, sight-glass, and vent fittings sized and positioned to match your pipework and safety requirements.
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Telemetry and Level Monitoring
Level sensors and telemetry integration for remote monitoring of tank content, dosing rates, and low-level alarms.
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Stand-Alone Dosing Cabinet
Direct connection to Polymaster’s stand-alone dosing system, housed within a lockable double-door cabinet for site-integrated chemical dosing.
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Talk to the Polymaster engineering team about your site’s specific dosing, monitoring, and connection requirements.
INSTALLATION AND SITE PREPARATION
Installation and Site Requirements
Polymaster’s self-draining tanks are designed for above-ground installation on an engineered plinth. Site preparation, anchorage, and connection requirements are set out in the Installation, Operation and Maintenance Manual and must be followed to maintain warranty.
Site Preparation and Foundation
A solid, flat, and level plinth suitable for the anchorage requirements of the tank is required. The plinth is engineered by the user and must be compatible with the anchorage load. Site selection should account for excessive wind or seismic forces, flood-prone areas, and safe distance from any equipment generating heat or flame. Tanks should be positioned to allow regular inspection, maintenance, and future removal or replacement.
Anchorage and Minimum Fill Levels
Tanks must be adequately restrained to ensure stability whether full or empty. To maintain stability in high wind loads on a near-empty chemical tank, minimum fill levels from the invert of the tank (under the outlet) must be observed:
SG 1.0 contents: minimum 778mm fill
SG 1.5 contents: minimum 588mm fill
The exception is when the tank is being emptied – maximum recommended empty duration is 48 hours, weather permitting. If this must be exceeded, appropriately designed temporary tethers must be installed from the top lifting lugs to the reinforced concrete slab.
Flexible Connections (Mandatory)
Flexible connections are required between the tank and all pipework to isolate the tank from external loads and vibrations. Failure to install appropriate flexible connections voids warranty. Minimum specifications:
- Axial compression ≥ 38mm
- Axial extension ≥ 15mm
- Lateral deflection ≥ 19mm
- Angular deflection ≥ 14°
Attach only full-face flanges to the flexible connection. Do not attach directly to the tank wall. Ensure adequate clearance between bolt ends and provide pipe support adjacent to the flexible connection.
Piping, Valves, and Fittings
All hoses, piping, and valves must be adequately supported independently of the tank. All fittings, valves, and piping should be shielded to prevent physical impact and protect personnel from chemical spray or leakage. No additional holes are to be drilled, and no additional fittings are to be installed into the tank wall beyond those supplied by Polymaster – doing so voids warranty.
Venting
Self-draining tanks cannot be pressurised and operate at atmospheric pressure only. Proper venting stops pressure or vacuum developing as the tank is topped up or emptied. The vent size should always exceed the size of the largest fill or discharge. Confirm the chemical being stored can be vented to atmosphere without prior treatment.
Temperature and SG Limits
Tanks are rated to a maximum specific gravity of 1.5. Continuous liquid temperature above 40°C is not recommended. The temperature of the chemical stored can produce different effects on polyethylene within the same chemical range – consult a Polymaster consultant if the application involves elevated or variable temperatures.
Inspection and Maintenance
Tanks must be inspected every 3 months (or to a total volume dispensed as required for the specific chemical or dispensing system, whichever occurs first) by a suitably qualified service engineer or technician. Visual inspection for stress cracking, UV degradation, weld condition, and fitting alignment is required. See the full IOM manual for the complete inspection schedule.
Warranty
Polymaster self-draining polyethylene tanks are guaranteed against material or manufacturing defect for 5 years from the date of invoice. Accessories and components are covered for 12 months (or per manufacturer warranty). Hoses, nozzles, and sensors are covered for 3 months.
DELIVERY AND DISTRIBUTION
Delivery Across Australia
Polymaster delivers self-draining tanks direct to site across Australia. Given the tank dimensions (3450mm diameter and up to 4149mm high for the 33,000L unit), site access, offloading equipment, and delivery vehicle clearance must be planned.
Preparing Your Site
Truck and trailer clearance required is 19 metres long, 5 metres high, and 3.5 metres wide. Check for low branches, powerlines, or narrow access points on your delivery route. A flat, clear area is required for offloading – Polymaster will discuss offloading equipment requirements (crane, forklift, or on-site lifting equipment) as part of the delivery booking. Our logistics team will contact you approximately seven days before arrival to confirm the delivery window and access requirements.
MORE CHEMICAL STORAGE SOLUTIONS FROM POLYMASTER
Explore Our Full Range of Chemical Storage Solutions
Self-draining tanks solve one problem – complete discharge on demand. If your operation needs continuous bulk chemical storage, sludge handling, dosing systems, or IBC-format storage, we have the full range.
Single-Walled Chemical Process Tanks:
Standard-configuration polyethylene chemical tanks for bulk chemical storage from 500L to 50,000L. The primary chemical storage option where full drainage is not required.
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Cone Bottom and Sludge Tanks:
Steeper-angled cone-bottom tanks for sludge handling, sedimentation, and processes where solids need to move to a single outlet.
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Chemical Dosing Units:
Complete dosing skids and stand-alone dosing cabinets that connect directly to the self-draining tank outlet for downstream chemical delivery.
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IBC Tanks and CageBuster IBC Tote:
Intermediate bulk container storage for smaller-volume chemical handling, transport, and site storage.
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Self-Bunded Chemical Tanks
Integrated secondary containment built into the tank. Suits sites without existing bund infrastructure.
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Ready to Specify a Self-Draining Tank for Your Site?
Talk to our engineering team. We’ll help you match the right capacity, material grade, and fitting configuration to your chemical, your site, and your process – from a standard 23,000L tank in 7032 through to a fully integrated 33,000L Chemical Grade tank with telemetry and dosing cabinet.
FAQs
Frequently Asked Questions
Everything you need to know about specifying and installing a Polymaster self-draining chemical tank.
What is the maximum specific gravity (SG) these tanks can store?
Polymaster self-draining tanks are rated to a maximum specific gravity of 1.5. This covers the working density of most commercial and industrial chemicals including concentrated acids, hypochlorites, caustics, and coagulants. If your chemical exceeds 1.5 SG, talk to a Polymaster engineer about a purpose-designed solution.
What’s the difference between Hexathene Chem and Hexathene Chem-Plus material?
Hexathene Chem is Polymaster’s standard chemical polyethylene, suitable for the majority of industrial chemicals in commercial use. Hexathene Chem-Plus is a specially formulated polyethylene developed for aggressive chemicals – including concentrated acids, hypochlorites, and caustics – where Hexathene Chem may show accelerated degradation. Both materials exceed the requirements of AS/NZS 4766. If you’re unsure which grade suits your chemical, request a chemical compatibility check with a Polymaster polymer chemist before ordering.
What outlet drain sizes are available?
Outlet drains are available in multiple sizes to suit the application. The drain sits at the centre of the sloping base and exits through a side channel, allowing virtually complete discharge of tank contents.
What’s the maximum operating temperature?
Continuous liquid temperature above 40°C is not recommended for these tanks. Temperature affects polyethylene performance and can vary in effect within the same chemical range. If your application involves elevated, variable, or intermittent high-temperature contents, consult a Polymaster consultant to confirm suitability.
Are there minimum fill requirements for tank stability?
Yes. To maintain stability under high wind loads on a near-empty tank, minimum fill levels from the invert of the tank are: 778mm for SG 1.0 contents, and 588mm for SG 1.5 contents. The exception is during scheduled emptying – the maximum recommended empty duration is 48 hours, weather permitting. If this must be exceeded, temporary tethers must be installed from the lifting lugs to the concrete slab.
Can I add my own fittings or modify the tank after delivery?
No. Additional holes must not be drilled and additional fittings must not be installed into the tank wall beyond those supplied by Polymaster. Modifications void the warranty. Specify all required fittings, nozzles, telemetry, and dosing connections at the time of order, and Polymaster will build them into the tank.
Can the tank be connected to a dosing system?
Yes. Polymaster’s self-draining tanks can be connected directly to a Polymaster stand-alone dosing system, housed in a lockable double-door cabinet for site-integrated chemical dosing. Telemetry, level sensing, and low-level alarms can also be specified.
What is the warranty period?
Polymaster polyethylene tanks are warranted for 5 years from the date of invoice against material or manufacturing defect. Accessories and components (agitators, frames) are covered for 12 months or per the component manufacturer’s warranty. Hoses, nozzles, and sensors are covered for 3 months. Warranty is conditional on the tank being installed and commissioned per the IOM manual by a suitably qualified person, above ground, on an engineered plinth, with flexible connections in place.