Motor Pumps

Petrol motor pump — what it is and when to choose one

A petrol motor pump is a water pump with its own gasoline engine, not requiring connection to the electrical grid. It works wherever a mobile and power-independent water source is needed — on construction sites (dewatering excavations, mixing concrete, pumping from basements), on farms (irrigation, emptying tanks and slurry pits), in fire services and civil protection (pumping water during floods), in emergency dewatering of flooded buildings and in road works. A typical motor pump delivers 500-1650 l/min (up to 100 m³ per hour) and can lift water up to 90 m (high-pressure version).

Three types of motor pumps by pumped medium

1. Clean water motor pumps

Clean water motor pumps deliver water without solids (or with very fine solids up to 5 mm) — from a tap, well, tank, pool, barrel or pond. Standard impeller cannot handle larger particles. Flow 115-1650 l/min, head 26-32 m (standard) or up to 90 m in high-pressure version (SERH50Z). Models: SEH25L (1", 5.5 kg — lightest), F80WP (3"), SERH50Z (2", 90 m head — for firefighting, long-distance irrigation).

2. Dirty water and semi-slurry motor pumps

Dirty water (semi-slurry) motor pumps deliver water with solids up to 8-9 mm diameter — sand, small stones, leaves, mud. Semi-open impeller handles particle flow without clogging. Main uses: dewatering construction excavations, emptying flooded basements after subsidence, draining pools after season, drainage works. Flow 500-900 l/min, head 26-29 m. Models: STV50X/STV80X (Koshin K180), STH50X/STH80X (Honda GX120/GX160).

3. Sludge motor pumps

Sludge motor pumps deliver the most contaminated media — sludge, thick deposits, liquids with large solids up to 27 mm diameter. Open impeller design with inspection cover allows cleaning the pump without disassembly. Typical use: emptying septic tanks and settling tanks, pumping sludge from biogas plants, farm work (slurry), emptying flooded excavation pits. Flow 700-1650 l/min, head 26-30 m. Models: KTH50X (700 l/min, 20 mm), KTH80X (1340 l/min, 27 mm), KTH100X (1650 l/min, 4" — largest).

Comparison table of 3 motor pump types

How to choose a motor pump — 4 key parameters

1. Medium type — this determines impeller choice. Clean water → standard, water with sand/stones → semi-slurry, sludge/manure → sludge pump. Wrong choice = clogged pump after 5 minutes of operation.

2. Required flow (l/min) — calculate how much water to pump per unit time. Example: emptying a flooded basement 50 m² × 30 cm of water = 15 m³ = 15,000 l. Pump 900 l/min will empty it in 17 minutes.

3. Maximum head (m) — vertical distance from water level to highest discharge point. Every 10 m of height = 1 bar pressure. A pump with max head 26 m won't lift water to the 4th floor of a building.

4. Connection diameter — from 1" (25 mm) to 4" (100 mm). Larger diameter = higher flow, but heavier hoses. Construction standard is 2"-3" (50-80 mm).

Frequently asked questions — petrol motor pumps

Which motor pump for dewatering an excavation or basement?

For dewatering excavations and basements choose a dirty water (semi-slurry) motor pump — water after flooding usually contains sand, mud and small debris. Models STV50X/STV80X (Koshin K180) or STH50X/STH80X (Honda GX120/GX160) with flow 500-900 l/min and handling solids up to 8-9 mm. A clean water pump will clog with sand within minutes. For very thick deposits (e.g. after excavation with mud) — sludge model KTH50X.

How much does a petrol motor pump cost?

Petrol motor pump price depends on type and flow. Smallest clean water motor pump (Koshin SEH25L, 1", 115 l/min) costs from 1,680 PLN net. Standard 2"-3" motor pumps (500-900 l/min) — from 1,400 PLN (STV50X) to 3,400 PLN (STH80X with Honda engine). High-pressure SERH50Z (90 m head) — 3,300 PLN net. Most powerful sludge pump KTH100X (4", 1650 l/min) — approx. 9,480 PLN net. Indicative prices, check current ones in the products above.

Honda or Koshin — which motor pump engine to choose?

Honda GX engines (GX120, GX160, GX240, GX340, GX390) are Japanese, premium, with lifespan of 3,000-5,000 engine hours with regular service. Koshin K180 engine is Japanese, dedicated to this brand's motor pumps, equally durable. Both are good choices — depends on brand preference and parts availability. Honda motor pumps are 20-30% more expensive (STH50X 2,800 PLN vs STV50X 1,780 PLN — same flow, engine difference). On Polish market Honda parts are more easily available.

Will a motor pump suck water from 8 m depth?

A standard motor pump will suck water from depth up to 8 m (theoretical maximum for centrifugal pump at atmospheric pressure 10.33 m minus hydraulic losses and water temperature). Practically effective suction is 5-7 m. If water is deeper (e.g. 12 m in a deep well), you need a submersible pump, not a petrol motor pump. Suction hose length further reduces flow: 2 m hose = -15%, 4 m = -25%, 7 m = -50%.

How much water will a motor pump deliver per hour?

Motor pump flow in l/min × 60 = l/hour. Example: STV80X (900 l/min) = 54,000 l/h = 54 m³/h. KTH100X (1650 l/min) = 99 m³/h. SEH25L (115 l/min) = 6.9 m³/h. These are values at zero head and short hose — in real conditions (4 m head, 7 m suction hose) flow drops by 30-50%. Practical flow: STV80X ≈ 30-40 m³/h, KTH100X ≈ 60-70 m³/h.

Can I use a motor pump for firefighting?

Yes, high-pressure motor pump SERH50Z (Honda GX200HR) is dedicated to fire services and civil protection — delivers 500 l/min at head up to 90 m, corresponding to 9 bars pressure at outlet. Standard motor pump delivers only 2.6-3.2 bars — too little for effective firefighting. For professional use by fire departments additional CNBOP certificates are required — check with the manufacturer. For extinguishing grass fires on private land SERH50Z is sufficient.

Does a motor pump require electricity or water supply?

No — a petrol motor pump is fully autonomous. Requires only gasoline (tank 2.0-6.1 l, runtime 1-3 hours per fill) and a suction hose immersed in the pumped medium. You can use it in a field, on a meadow, on a construction site without utility connections, during power grid failure, during flooding. This is the main advantage over an electric submersible pump — independence and mobility (weight 5.5-78 kg, can be transported in a car trunk).

What additional equipment do I need for a motor pump?

Every motor pump requires: suction hose (with strainer basket and check valve, 4-7 m length — Koshin/Toolsa from 286-660 PLN net), discharge hose (8-20 m, from 215-610 PLN net) and Storz aluminum couplings for quick connection (28-72 PLN per piece). For long-term work an engine hour meter (for service planning) and engine service kit (air filter, oil, spark plug — every 100 engine hours) are recommended. Full range of accessories in pump accessories.