This is a control method to suppress hunting (excessive back-and-forth between the target value) caused by excessive chemical injection in pH neutralization.
The amount of chemical required for pH neutralization decreases as the target pH value is approached, but if the metering pump is operated at a constant rate, the target pH value will be greatly reduced due to over-injection of the chemical (e.g., ON-OFF only control). To prevent this, continuous operation is performed when the pH value is far from the target pH value, intermittent operation can be used to gradually bring the pH value closer to the target value. This control method is called time-proportional control. By varying the pump operation time proportionally to the target pH value, this prevents excessive injection of chemicals and ensures smooth adjustment to the target pH value.
Tohkemy Corporation
Tohkemy TPC Continuous Type Automatic pH Neutralizer Model Water Treatment Systems

Manufacturer: Tohkemy Corporation
Model: TPC
Features
Continuous Flow Neutralization: Raw water flows continuously into the tank, where chemicals are injected and agitated based on pH, then naturally discharged.Proportional Control: Features time-division proportional dosing for optimal pH adjustment.
Residence Time: Designed with a 15-minute retention time for reliable, complete reaction.
Tank Materials: Standard SS400 with modified epoxy coating; optional SUS, FRP, or PVC.
pH Range (Single-Stage): Handles raw water between pH 4 and 11.
Multi-Stage Systems: Raw water exceeding pH 4–11 requires 2- or 3-stage treatment (coarse neutralization in stage 1, fine adjustment in subsequent stages).
Testing Services: Neutralization titration tests on sample water are available (actual chemical consumption may exceed theoretical values due to reaction inhibitors).What is Time-Proportional Control

Applications
General factory wastewater/ Hospital wastewater/ Laboratory wastewater/ Concrete plant wastewater/ Rainwater in factories /Cleaning wastewater/ Boiler wastewater/ Adjustment to a pH value suitable for treatment
Specifications
Unit Specifications
| Model | Amount of treated water | Capacity of neutralization tank | Agitator (medium speed type) | Chemical pump discharge rate (ml/min) | Chemical injection tank | Approximate dimensions (m) | Equipment mass (Approx.) | Operating mass (Approx.) | |
|---|---|---|---|---|---|---|---|---|---|
| 60Hz | 50Hz | ||||||||
| TPC-01 | 1m3/hr | 0.25m3 | NKA4-002 0.2kW | 6~30 | 5~25 | 50L | 0.7W×1.4L×1.6H | 200kg | 500kg |
| TPC-03 | 3m3/hr | 0.75m3 | NTA4-002 0.2kW | 14~70 | 12~58 | 100L | 1W×1.73L×1.72H | 500kg | 1,400kg |
| TPC-06 | 6m3/hr | 1.5m3 | NTA4-004 0.4kW | 24~120 | 20~100 | 200L | 1.4W×2.08L×1.78H | 800kg | 2,500kg |
| TPC-10 | 10m3/hr | 2.5m3 | NTA4-007 0.75kW | 60~300 | 50~250 | 200L | 1.6W×2.25L×2.265H | 1,000kg | 3,700kg |
| TPC-20 | 20m3/hr | 5.0m3 | NTA4-015 1.5kW | 120~600 | 100~500 | 300L | 2W×2.77L×2.605H | 1,600kg | 6,900kg |
| TPC-30 | 30m3/hr | 7.5m3 | NTA4-022 2.2kW | 200~1000 | 160~800 | 500L | 2.5W×3.36L×2.815H | 2,000kg | 10,000kg |
Product Specifications
| Standard specification | Option | |
|---|---|---|
| Installation location | Indoor | Outdoor |
| Raw water temperature | Max 40℃ | - |
| Supported Chemicals | Sodium hydroxide, Sulfuric Acid, Hydrochloric Acid | - |
| Tank material | SS(TPC-01 PVC ONLY) | SUS304、FRP、PVC |
| Painting, internal surface treatment methods | Modified epoxy resin | Rubber lining, FRP lining |
| External input-output | “External interlocking input Batch alarm output(No-voltage contact output)” | No External interlocking input Individual alarm output (No-voltage contact output) |
| Power supply voltage | 3P200V | Operatable with a different voltage |
| Control Method | pH single control(Acidic _or Alkaline) | pH dual control |
| Equipment | Raw water pump inflow type(Circuit only) Neutralization tank Agitator for neutralization tank pH regulator pH electrode Common base Control panel Chemical tank Chemical injection pump | Measuring tank Flowmeter for raw water intake Raw water pump Raw water tank level switch pH recorder (with alarm circuit) 2- _or 3-stage treatment Treated water return valve Discharge pump Chemical tank level switch Liquid barrier for chemical tank Neutralization tank lid Neutralization tank drain valv |
*Please contact us for details on 2- _and 3-stage equipment _and other customizations
Flow Sheet


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