Product Report: Thompson’s 4JSCM pump

Looking closely at the 4-inch diesel pump market, Thompson Pump & Manufacturing engineers noticed contractors and municipal sewer systems were requesting pumps capable of passing 3-inch solids, typically handled by 6-inch-and-larger units. At the same time, however, these clients didn’t need the higher flows provided by the larger pumps.

“So our first target was to get our 4-inch pump to handle 3-inch solids,” says Dale Conway, vice president of engineering for Thompson. Handling larger solids in the past, though, meant a pump had to have a higher-horsepower engine. “So you saw a mixture of smaller pumps that didn’t handle the big solids and larger pumps that did, but didn’t do it efficiently,” he says.

Thompson started with a closed-style impeller design used by makers of submersible pumps, but new to engine-driven pumps. Engineers then redesigned the suction portion of the impeller and tackled the pump’s casings and bearings so they could withstand greater loads. The result is the company’s new 4JSCM 4-inch dry-priming pump, capable of handling 3-inch solids. “We describe it as being able to take a baseball and have it go through the pump without getting stuck,” Conway says.

The design also allowed the company to put a smaller engine on the pump, important for two reasons. First, it burns about half the fuel of the previous 4-inch-pump engine. “If a pump runs continuously throughout the year, this could literally save you thousands of dollars,” Conway says. Second, it allowed engineers to reduce the physical size and weight of the pump, making it easier to move around the jobsite.

The differences were remarkable: Compared to the company’s previous 4-inch pump, the 4JSCM offers a reduction of 42 horsepower and 2,500 pounds.

In addition, Thompson addressed noise concerns with an optional 500-pound canopy, which covers the entire pump, decreasing sound levels by 15 decibels. “Besides the noise reduction,” Conway says, “the canopy is a theft deterrent since it allows you to lock up the pump.”

The pump features Thompson’s Enviroprime system, which prevents blow-by such as sewage, debris and chemicals from discharging on the ground, and separates air and water, keeping the pump’s venturi from clogging and shutting down. An optional auto start/stop system shuts the pump off when the water level is too low for it to run efficiently. “Since the pump can run dry, this can save a lot of fuel during non-productive times,” Conway says.