| Drying Capacity | Confirm both wet-feed and dry-product capacity. A quoted throughput without feed moisture, discharge moisture, material density, and residence time is not comparable. | Written capacity statement showing feed rate, inlet moisture, target outlet moisture, bulk density, particle-size distribution, and operating temperature. | Dryer capacity is governed by evaporative load and material behavior, not only by the machine's nominal dimensions. | Comparable Data | Compare suppliers using the same process conditions. |
| Moisture-Removal Performance | Require a guaranteed outlet-moisture range and define the permitted moisture variation across the product stream. | Factory test report, representative sample test, moisture measurement method, and documented acceptance criteria. | Consistent final moisture helps protect product quality, storage stability, and downstream processing. | Critical | Specify test method and sampling frequency in the contract. |
| Energy Efficiency | Evaluate specific energy consumption in kWh per tonne of water evaporated, rather than using only motor power or installed heating capacity. | Energy balance covering electrical power, thermal input, exhaust losses, air volume, inlet and outlet temperatures, and evaporation rate. | Specific energy consumption allows fair comparison between different dryer sizes, heating systems, and operating conditions. | Critical | Request measured data from a test using material similar to yours. |
| Vibration System | Adjustable vibration frequency and amplitude should be matched to material flow, bed depth, and residence-time requirements. | Operating envelope, vibration-isolation design, bearing specifications, lubrication schedule, and dynamic-load calculations. | Correct vibration control supports uniform conveying and reduces excessive mechanical stress, noise, and product breakage. | Technical Review | Verify settings under actual production load, not only at no-load conditions. |
| Temperature Control | Independent control of process-air temperature, product temperature, and exhaust temperature is preferable for heat-sensitive products. | Control-loop diagram, sensor accuracy, alarm limits, response time, and calibration certificates. | Stable temperature control reduces overheating risk and improves repeatability between production batches. | Critical | Confirm product-temperature limits and control accuracy in the specification. |
| Airflow and Heat Recovery | Assess recirculation, exhaust control, insulation, and heat-recovery options. Heat recovery should be evaluated using measured thermal savings. | Airflow diagram, fan curve, duct-pressure calculations, insulation specifications, and estimated or measured heat-recovery performance. | Air management often has a larger effect on operating cost than the vibratory drive alone. | Efficiency Review | Check whether stated savings include fan power and cleaning losses. |
| Product Quality and Handling | Product-contact surfaces should be compatible with the material, cleaning method, temperature, and corrosion environment. | Material certificates, surface-finish specification, weld-quality records, seals, gaskets, and cleanability details. | Suitable construction reduces contamination, corrosion, wear, and unplanned sanitation downtime. | Critical | Define surface finish and material requirements before quotation. |
| Safety and Compliance | Electrical and mechanical safeguards should align with the destination country's regulations and the site's risk assessment. | Risk assessment, guarding details, emergency-stop layout, electrical schematics, conformity documentation, and applicable test records. | Compliance affects import approval, installation acceptance, operator safety, and insurance requirements. | Mandatory | Confirm local voltage, frequency, enclosure rating, and documentation language. |
| Reliability and Maintainability | Look for accessible wear parts, condition-monitoring provisions, defined preventive-maintenance intervals, and documented spare-parts availability. | Bill of critical spare parts, maintenance manual, bearing-life calculations, recommended inspection intervals, and service response terms. | Maintainability directly influences uptime and the total cost of ownership over the equipment life. | Lifecycle Value | Price critical spares and service travel before placing the order. |
| Testing and Acceptance | Use a documented factory acceptance test and, where practical, a site acceptance test based on agreed process conditions. | Test protocol covering throughput, final moisture, energy input, vibration, noise, temperature, and safety functions. | Performance guarantees are meaningful only when measurement methods and operating conditions are clearly defined. | Mandatory | Link final payment and warranty conditions to agreed acceptance criteria. |
| Total Cost of Ownership | Compare purchase price, installation, utilities, labor, maintenance, consumables, downtime, and expected service life. | Five- to ten-year operating-cost model using transparent assumptions for energy price, annual hours, maintenance, and production volume. | A lower initial price can result in higher long-term costs if energy use, maintenance, or downtime is excessive. | Financial Review | Use the same production schedule and energy prices for every quotation. |