Choosing a 125QJB Deep Well Submersible Pump: Working Requirements and Integration Fit

1. Start with the well diameter

The published model reference lists the applicable well diameter for the 125 series as "125 above" (mm), and gives a maximum unit radial size of 118 mm. In practice, this means the 125QJB is intended for wells with a diameter of 125 mm or more.

If your well is larger and you need more flow or head than the 125 series offers, the same product family includes larger series. Each one is published with its own well-diameter range:

2. Match flow and head to the published 125 series models

The 125 series reference table is labelled as a partial model reference. All the models listed below are published at 2850 r/min and a rated voltage of 380 V. The model code shows the rated flow (m³/h) followed by the head (m). For example, 125QJ10-48 means 10 m³/h at 48 m.

5 m³/h group (water pump efficiency 53%, 40 mm outlet)

10 m³/h group (water pump efficiency 60%, 50 mm outlet)

15 m³/h group (water pump efficiency 63%, 50 mm outlet)

The product data also says that pump output should be kept between 0.7 and 1.2 times the rated flow. The well must also be able to supply that output continuously. Choose a model whose rated flow suits the tested yield of your well, rather than simply picking the highest-flow option. If you need more than 15 m³/h or more head than the models listed above, ask for the full model list or look at a larger series that fits your well diameter.

3. Check the power supply

The published supply condition is three-phase AC 380 V (±5%), 50 Hz (±1%). The motor uses a variable-frequency winding design, and the product description says it runs stably over the long term between 1 Hz and 50 Hz. Because the target markets for this site cover several regions, check your local supply voltage and frequency against these figures. If they differ, confirm suitability with the manufacturer before you order. Do not assume compatibility.

4. Confirm water quality limits

The 125QJB is specified for water within these limits:

• Water temperature not higher than 20 °C
• Solid impurities (mass ratio) not greater than 0.01%
• pH 6.5–8.5
• Hydrogen sulfide not greater than 1.5 mg/L
• Chloride ion not greater than 400 mg/L

If a water analysis shows values outside any of these limits, this standard recommendation does not apply. That includes warmer water, sandy water, or water with high chloride or hydrogen sulfide levels. In that case, discuss it with the supplier. The product page says the company takes on OEM processing and can design non-standard submersible motors and pumps to user requirements. The specific capabilities for your case still need to be confirmed.

5. Verify installation conditions

The published conditions of use set clear limits for installation:

• Fully submerged: the pump must be completely under water, at a submersion depth of no more than 70 m.
• Bottom clearance: the bottom of the pump must be at least 3 m above the bottom of the well.
• Vertical only: the well should be straight, and the pump may only be used vertically, never horizontally or tilted.
• Motor filling: the motor has a closed or water-filled wet structure. Before use, the motor cavity must be completely filled with clean water, with no false fill. The water-filling and air-release bolts must then be tightened. Otherwise the pump must not be used.
• No dry running: testing the pump with no load and no water is strictly prohibited.

If the borehole is crooked, too shallow to give 3 m of bottom clearance, or would need a submersion depth over 70 m, the 125QJB is not a suitable choice as specified.

6. Plan cables and protection

The pump must be used with a cable that meets the specified requirements and with an external overload protection device. When planning the control panel, use the rated current of your chosen model from the tables above to size the protection. Confirm cable specifications with the supplier, because they are not given in the published excerpt.

7. Documentation to request

The product implementation standards published for the 125QJB are GB/T2816-2014 (well submersible pump) and GB/T2818-2014 (well submersible asynchronous motor). These are the stated implementation standards, not third-party certifications. If your project needs specific certifications, test reports, pricing or delivery commitments, ask Hebei Aochite Water Supply and Drainage Equipment Technology Co., Ltd. for them in writing. This guide does not state them.

Quick fit checklist

• Well diameter is 125 mm or more
• Required duty is close to one of the 5, 10 or 15 m³/h models listed, at a suitable head
• Well yield can support continuous operation at 0.7–1.2 times the rated flow
• Site supply matches three-phase 380 V ±5%, 50 Hz ±1%, or a variance has been confirmed
• Water analysis is within the temperature, solids, pH, H₂S and chloride limits
• Vertical installation, fully submerged, no more than 70 m deep, at least 3 m above the well bottom
• Correct cable and external overload protection are planned

If every item checks out, the 125QJB Deep Well Submersible Pump is a documented match for your conditions. If any item fails, either choose a different series or ask about a non-standard design.