“What size pump do I need?” is the first question every buyer asks. The answer depends on three numbers: your well diameter, your required flow, and your required head. This page gives you a fast reference table from our selection manual, so you can find candidate models yourself in two minutes. Then our engineers confirm the final choice.
All data below is quoted directly from our QJ/QJT selection manual. Nothing is estimated.
Step 1: Match Your Well Diameter to a Pump Series
The well casing decides which series can physically fit. The flow number in the series name (for example the “80” in 250QJ80) is the design flow in m³/h.
| Well diameter (mm) | Approx. inches | Series in this size | Flow range (m³/h) | Head range (m) | Max. unit outer diameter |
|---|---|---|---|---|---|
| 150 mm | 6″ | 150QJT5 / 10 / 20 / 32 | 5–32 | 18–450 | 143 mm |
| 175 mm | 7″ | 175QJ25 / 32 / 50; 175QJT20–70 | 20–70 | 24–330 | 168 mm |
| 200 mm | 8″ | 200QJ20–100; 200QJT20–100 | 20–100 | 12–420 | 184 mm |
| 250 mm | 10″ | 250QJ80–140; 250QJT50–160 | 50–160 | 15–600 | 233 mm |
| 300 mm | 12″ | 300QJ200 / 240; 300QJT200–350 | 200–350 | 20–270 | 281 mm |
| 350 mm | 14″ | 350QJT400 / 500 / 600 | 400–600 | 17–119 | 330 mm |
Ranges cover different models and stages. Maximum flow and maximum head do not occur simultaneously on a single pump.
The series above cover wells from 150 mm (about 6″) to 350 mm (about 14″). The product line as a whole is rated for well diameters from 150 mm to 400 mm. Our smallest series is for 150 mm (6″) wells; smaller boreholes are outside our range.
Step 2: Typical Models at a Glance
Here are typical models from the manual, one or two per well size. “Stages” is the number of impellers. Power is the matched motor rating (kW); for some models the manual lists different motor types (YQS / JQS / YQS·T), shown together.
| Model | Flow (m³/h) | Head (m) | Stages | Motor (kW) | Min. well |
|---|---|---|---|---|---|
| 150QJT20-80/8 | 20 | 80 | 8 | 7.5 | 150 mm |
| 150QJT5-150/15 | 5 | 150 | 15 | 4 | 150 mm |
| 175QJ50-78/6 | 50 | 78 | 6 | 18.5 | 175 mm |
| 200QJ50-78/6 | 50 | 78 | 6 | 18.5 / 17 / 18.5 | 200 mm |
| 200QJ80-33/3 | 80 | 33 | 3 | 11 | 200 mm |
| 250QJ80-80/4 | 80 | 80 | 4 | 30 / 28 / 30 | 250 mm |
| 250QJT50-90/3 | 50 | 90 | 3 | 22 | 250 mm |
| 300QJ200-80/4 | 200 | 80 | 4 | 75 / 70 / 75 | 300 mm |
| 300QJT300-66/3 | 300 | 66 | 3 | 90 / 92 / 87 | 300 mm |
| 350QJT500-44/2 | 500 | 44 | 2 | 90 / 92 / 110 | 350 mm |
The full manual contains a 555-model selection table across 46 series — heads from 6 m to 600 m, flows from 5 to 600 m³/h, motor power from 3 to 250 kW. If the table above does not cover your duty point, send us your parameters: with 555 rows the engineers can usually find a candidate, and if your duty point falls outside the table, we confirm with the factory.
(One note on numbers: the 555-model figure counts the model-by-model rows in our 2007 selection manual. You will also see “10 series, 800+ specifications” in our company materials — that is the product-line summary figure from the manual’s overview. The two come from different editions and levels of the same catalog.)
Step 3: How to Read a QJ Model Number
Our model numbers tell you the whole duty point. Take 250QJ80-80/4 as the example:
- 250 — minimum well diameter: 250 mm
- QJ — borehole submersible pump (national-standard type)
- 80 — design flow: 80 m³/h
- 80 — design head: 80 m
- 4 — number of stages: 4
The QJT series works the same way, for example 250QJT80-120/4: 250 mm well, 80 m³/h, 120 m head, 4 stages. QJT is our newer high-efficiency design — its single-stage head is higher than the QJ type, so a QJT pump needs fewer stages for the same head.
So when you see a model number, you can check at once: does it fit my well? Does it cover my flow and head? If yes, it is a candidate — the final duty point is still confirmed by our engineers against the pump curve.
Step 4: Check Head and Flow Together
A common mistake is to choose only by flow. A 250QJ80 pump exists in many head versions — from 250QJ80-20/1 (20 m head, 7.5 kW) up to 250QJ80-240/12 (240 m head, 90 kW). Same flow, very different pumps and prices.
Remember: the head you need is the Total Dynamic Head, not the well depth. If you are not sure how to calculate it, read our worked example: Well Depth Is Not Pump Head: How to Calculate TDH. For the full five-parameter method, see: How to Choose a Borehole Pump: 5 Parameters You Must Know.
A last tip for importers and drillers: when you stock pumps for resale, tell our engineers the well depths and water levels you see most often in your market. They can suggest which head versions of each flow series are most likely to cover your typical projects before you build your stock list.
Step 5: Confirm Water Quality and Power Supply
The model number fixes flow and head. Two things it does not fix:
Water quality. Our manual limits are: water temperature not higher than 20 °C, solids not more than 0.01% by mass, pH 6.5–8.5, hydrogen sulfide not more than 1.5 mg/L, chloride ions not more than 400 mg/L. If your well water exceeds any of these — high-chloride water is common in many parts of Africa — do not order on guesswork. Send the test report. Suitability and material options must be confirmed with our engineers.
Power supply. Standard motors are 380 V ±5%, 50 Hz ±1%, three-phase. We can customize for 60 Hz, 220 V, or 660 V. Other voltages: confirm with our engineers. Also tell us if your grid is weak — large motors can use reduced-voltage, soft, or variable-frequency starting.
What We Supply With the Pump
A complete borehole pumping unit is more than the pump end. It includes the pump stages, the submersible water-filled motor, the rising pipe and pump base, the cable, a gate valve, and the control panel. Our selection manual lists the matched motor and a reference copper cable cross-section for every model (2.5–95 mm², with double cables for large motors). The reference size is a starting point: the final cable specification depends on motor power, cable length, installation method, and voltage drop, and is confirmed with our engineers for your installation.
Every control panel must have short-circuit, phase-loss, and overload protection. The motor cavity must be filled with distilled or clean water before installation and must never run dry.
One more note for importers: the factory has confirmed that every model in the 555-model selection table — including older series such as 175QJ25, 300QJT200, and 350QJT400 — can still be produced. For any model you plan to reorder regularly, please confirm the current lead time with our engineers before you promise a delivery date to your customer.
Send Us Three Numbers, Get a Selection
You do not need to finish the selection alone. Send us:
- Required flow rate (m³/h)
- Required head / TDH (m)
- Well casing inner diameter (mm)
Our engineers will check the manual’s 555-model table and reply with candidate models and matched motor power; the final model, duty point, and cable specification are confirmed against the pump curve and your installation details. Use our online pump selector or contact us directly. You can also browse the full range on the borehole pumps product page.
— Ganquan Pump Export Team