Top OEMs for Emergency Bypass & Temporary Pumping Systems

1. Introduction

In the hydraulic architecture of municipal and industrial wastewater systems, continuity of service is the paramount directive. While permanent infrastructure—lift stations, treatment plants, and gravity mains—forms the backbone of these systems, the ability to bypass these components during failure, maintenance, or rehabilitation is a critical engineering requirement. Emergency bypass and temporary pumping systems represent the “safety valve” of the utility sector, ensuring that when primary mechanical or structural systems are offline, flow is conveyed without environmental release, regulatory violation, or public health compromise.

The selection of Original Equipment Manufacturers (OEMs) for these systems differs fundamentally from selecting permanent process pumps. Permanent pumps are optimized for a specific, narrow operating point on a system curve. In contrast, temporary and bypass pumps must be engineered for extreme versatility. They must handle widely varying flow rates, fluctuating static heads, erratic solids loading, and often adverse suction conditions that would cause cavitation in standard process equipment. For the consulting engineer and utility operator, the bypass pump is not merely a commodity rental item; it is a critical asset that must perform flawlessly under the most challenging conditions, often unmanned and in proximity to residential or sensitive environmental zones.

Regulatory context drives much of the engineering rigor in this category. The U.S. Environmental Protection Agency (EPA) and state-level environmental quality departments enforce strict penalties for Sanitary Sewer Overflows (SSOs). A bypass system failure—whether due to failure to prime, clogging, or mechanical breakdown—can result in immediate illicit discharge. Consequently, the engineering specification for these units prioritizes reliability, solids-handling capability, and autonomous operation (such as automatic self-priming) over pure hydraulic efficiency.

This article examines the primary OEMs defining the landscape of emergency bypass and temporary pumping. It focuses on the technical nuances of their equipment, distinguishing between vacuum-assisted priming systems, submersible electric topologies, and self-priming centrifugal designs. The objective is to provide engineers and plant managers with a clear, unbiased framework for specifying equipment that aligns with the operational realities of sewer bypass, dewatering, and emergency response.

2. How to Select This System or Equipment

Selecting a temporary pumping system requires a shift in engineering mindset from “efficiency at design point” to “reliability across the envelope.” Engineers must evaluate the system’s ability to operate intermittently, handle significant air entrainment, and manage variable viscosity and solids content. The following technical criteria are essential for specification and selection.

Functional Role and Operating Conditions

The functional role of a bypass pump is to convey fluid from a temporary suction point (often a manhole or wet well) to a temporary or permanent discharge point, bypassing a compromised or offline section of infrastructure. Operating conditions in these scenarios are rarely ideal.

• Suction Lift vs. Positive Suction Head: Most surface-mounted bypass pumps must operate in a suction lift condition, often exceeding 20 feet (6 meters). This requires robust priming systems capable of evacuating air from the suction line and maintaining prime during low-flow/snore conditions.
• Variable Flow Rates: Unlike a pump station designed for peak flow, a bypass pump may see diurnal flows ranging from near zero to peak wet weather events. The pump and its driver (engine or VFD-driven motor) must be capable of significant turndown without overheating or damaging the mechanical seals.
• Solids Handling: The nature of raw sewage in bypass applications often includes large solids, rags, and stringy fibrous material. Impeller geometry (open, enclosed, semi-recessed, or chopper) must be selected based on the specific risk of clogging.

Reliability and Redundancy

In bypass operations, redundancy is not optional; it is a statistical necessity. The standard engineering approach is an N+1 configuration, where the primary pump(s) can handle the peak design flow, and a standby unit is fully piped and automated to take over immediately upon failure.

Reliability analysis focuses on the “weak links” of temporary systems:

• Priming Systems: Failure to prime is the leading cause of bypass failure. Engineers must evaluate whether the OEM uses a venturi-based system, a vacuum pump, or a diaphragm pump for priming. Vacuum-assisted systems generally offer faster priming and higher air handling capacities but add mechanical complexity (oil-flooded vanes, belts, etc.).
• Seal Integrity: Bypass pumps often run dry or in “snore” mode. The mechanical seal design—typically silicon carbide or tungsten carbide faces with oil bath lubrication—must be capable of surviving indefinite dry running without thermal cracking.

Materials and Construction

Construction materials dictate the unit’s longevity and application suitability.

• Volute and Impeller: Standard municipal sewage pumps typically utilize ductile iron or cast iron. However, for abrasive applications (stormwater with sand/grit) or industrial effluents, High Chrome Iron or CD4MCu duplex stainless steel provides necessary wear and corrosion resistance.
• Chassis and Enclosure: For portable diesel units, the skid or trailer design is structural. Sound-attenuated enclosures are critical for urban deployments, with specifications typically requiring <70 dBA at 23 feet. The enclosure must also provide fluid containment (bunding) to prevent fuel or oil spills from contaminating the site.

Common Failure Modes and Mitigation

Understanding how these pumps fail allows engineers to write tighter specifications.

• Air Entrainment: If the suction line is not perfectly sealed, or if the water level drops too low (vortexing), the pump can lose prime. OEMs with superior air handling capabilities (50+ CFM vacuum pumps) are preferred for fluctuating levels.
• Ragging: Traditional non-clog impellers can still foul with modern non-dispersible wipes. Chopper pumps or pumps with serrated wear plates and open impellers mitigate this but may sacrifice some hydraulic efficiency.
• Fuel Contamination/Starvation: For diesel units, fuel logistics are a major operational burden. Extended run fuel tanks (24+ hours) and telematics that alert operators to low fuel levels are standard spec requirements.

Lifecycle Cost and Maintenance

While often rented, purchased assets have significant lifecycle considerations. Tier 4 Final diesel engines require Diesel Exhaust Fluid (DEF) and sophisticated maintenance of Diesel Particulate Filters (DPF). Engine loading becomes critical; running a Tier 4 engine at light loads for extended periods can cause “wet stacking” and DPF clogging. Electric drive units eliminate this complexity but require reliable site power or large generators.

3. Comparison Table

The following table contrasts the five key OEMs in the emergency bypass and temporary pumping sector. It highlights their primary technological approach (e.g., vacuum-assisted vs. submersible vs. self-priming), key strengths relevant to municipal and industrial engineering, and specific limitations that specifiers should consider. This comparison assumes a standard municipal wastewater or stormwater context unless otherwise noted.

OEM	Core Technology Focus	Typical Applications	Strengths	Limitations / Considerations
Thompson Pump	Compressor-Assisted Priming (Enviroprime) & Rotary Wellpoint	Sewer Bypass, Wellpoint Dewatering, Construction Site Drainage	High air-handling capacity via oil-less compressor priming system; robust heavy-duty construction; excellent dry-run capabilities.	Large physical footprint for some high-head models; compressor systems require specific maintenance intervals separate from the pump end.
Godwin (Xylem)	Venturi/Ejector Priming (Dri-Prime) & Submersible Integration	Municipal Bypass, Flood Control, Industrial Dewatering	Industry standard for rental fleets; Field Smart Technology (SCADA) integration; Flygt N-Technology impellers available in diesel sets for clog resistance.	Venturi priming requires compressed air, adding a system component; high brand recognition often commands a premium price point.
Tsurumi	Electric Submersible Pumps	Deep Wet Wells, Sump Dewatering, Sand/Slit Laden Water	No priming required (submerged); Anti-Wicking Cable Entry prevents water ingress; extremely durable in abrasive applications; compact.	Requires electrical infrastructure or generator; generally not suitable for suction lift applications (must be submerged); limited large-diesel options compared to others.
Gorman-Rupp	Self-Priming Centrifugal (Standard Prime)	Lift Station Backup, Permanent Bypass, Sludge Transfer	Serviceability (removable cover plate for unclogging); reliability (fewer moving parts than vacuum-assisted units); high solids handling.	Relies on fluid retention for priming (standard self-priming), which is slower than vacuum-assist on long suction lines; limited dry-run capability without external assist.
BJM Pumps	Severe Duty / Shredder Submersibles	Industrial Wastewater, High-Temperature Effluent, Abrasive Slurries	Specialized metallurgy (High Chrome, 316SS) for corrosion/abrasion; integrated shredders for heavy solids; high-temperature options.	Niche focus on submersibles; less focus on large-scale diesel surface pumps for general municipal bypass; lower flow ranges compared to massive axial flow units.

4. Top OEMs / System Integrators

Thompson Pump

Thompson Pump is a cornerstone manufacturer in the North American dewatering and bypass market. Their engineering philosophy leans heavily towards robust, heavy-duty construction designed for the rigors of the construction and rental industries. For municipal engineers, Thompson is frequently specified for their “Enviroprime” system.

Technical Analysis: The core differentiator for Thompson is the OVT (Oil-less Vacuum Technology) and compressor-assisted priming systems. Unlike venturi systems that might rely on engine bleed air or separate compressors, Thompson’s priming system is designed to handle large volumes of air rapidly, making them exceptionally effective for wellpoint dewatering and long suction lines where air entrainment is a constant variable. Their pumps utilize an air-water separation tank that prevents pump fluid from discharging onto the ground, a critical feature for environmental compliance.

Engineering Merit: Thompson pumps are noted for their high-head capabilities and heavy-duty cast iron construction. They offer a diverse range of solids-handling impellers, including enclosed two-vane and three-vane designs optimized for passing 3-inch spheres. Their “silent knight” enclosures are engineered for superior sound attenuation, making them suitable for residential sewer bypass projects.

Godwin (Xylem)

Godwin, a brand within the Xylem portfolio, is perhaps the most ubiquitous name in temporary pumping globally. The “Dri-Prime” series essentially defined the automatic self-priming diesel pump category. As part of Xylem, Godwin benefits from cross-pollination with Flygt technologies, specifically regarding impeller design and motor efficiency.

Technical Analysis: The Godwin Dri-Prime system utilizes a venturi-based air ejector or a vacuum pump, depending on the specific model generation and application. This allows the pump to prime from dry to 28 feet of static suction lift. A significant engineering advantage is the integration of Xylem’s “N-Technology” self-cleaning impellers into the Godwin HL and NC series. The N-impeller uses a backswept leading edge and a relief groove in the volute to push solids away from the center, drastically reducing ragging incidents in raw sewage applications.

Engineering Merit: Godwin units are highly integrated with telemetry. The “Field Smart Technology” (FST) allows operators to monitor RPM, fuel level, engine temperature, and suction/discharge pressures remotely. For critical municipal bypasses, this data transparency allows for predictive dispatching of fuel trucks and maintenance crews, reducing the risk of unexpected downtime. Their fleet depth ensures that virtually any flow and head combination can be met, from small 4-inch pumps to massive high-flow flood control units.

Tsurumi

Tsurumi Manufacturing Co., Ltd. takes a fundamentally different approach compared to Godwin or Thompson. While they do offer engine-driven pumps, their dominance and engineering excellence lie in electric submersible pumps. For engineers dealing with deep lift stations or applications where suction lift physics make surface pumps impractical, Tsurumi is a primary specification.

Technical Analysis: Tsurumi’s defining technical feature is the “Anti-Wicking Block.” In submersible pumps, water often enters the motor housing through the power cable due to capillary action (wicking) if the cable jacket is damaged or the tip is submerged. Tsurumi creates a sealed section at the cable entry that prevents this water intrusion, significantly extending stator life. Additionally, their pumps often feature dual silicon carbide mechanical seals located inside an oil chamber, not in the pumped medium, offering superior thermal protection.

Engineering Merit: Tsurumi pumps are often specified for their abrasion resistance. They frequently use high-chrome iron impellers and agitators, making them ideal for stormwater bypasses where sand and grit load is high. Because they are submersible, they eliminate the priming variable entirely—if the pump is in water, it works. This simplifies control logic and removes the vacuum system as a failure point, provided electrical power is reliable.

Gorman-Rupp

Gorman-Rupp is the premier American manufacturer of self-priming centrifugal pumps. Unlike the vacuum-assisted units from Thompson or Godwin, Gorman-Rupp’s classic Super T and Ultra V series rely on a large volute reservoir to retain fluid, allowing the pump to re-prime itself after an initial manual fill. While they produce engine-driven packages, their technology is most often seen in permanent lift stations, though their mobile units are widely used for bypass.

Technical Analysis: The engineering philosophy here is “maintainability.” The pumps feature a removable cover plate that allows an operator to access the impeller and wear plate to clear a clog in minutes without disconnecting piping or using special tools. From a hydraulic standpoint, because they do not use a vacuum pump, they have fewer moving parts. However, the physics of standard self-priming limits their air handling capacity compared to vacuum-assisted units; they are slower to prime on long, empty lines.

Engineering Merit: For bypass applications involving heavy sludge or where simplicity is valued over rapid priming speed, Gorman-Rupp is unmatched. Their “Eradicator” solids management system creates a self-cleaning function similar to a chopper, but without the sharp blades that dull over time. Engineers specify Gorman-Rupp when the maintenance staff needs equipment they can service easily in the field with basic hand tools.

BJM Pumps

BJM Pumps (now part of Industrial Flow Solutions) occupies a specialized niche: severe duty and industrial submersibles. While they may not be the first choice for a clean water bypass, they are the “go-to” for industrial wastewater, chemical plant bypasses, or municipal applications with extreme challenges (high temperature, high abrasion, or shredding requirements).

Technical Analysis: BJM specializes in metallurgy. Their pumps are available in 316 Stainless Steel, Cast Iron, and proprietary hard-metal alloys (Fahrenheit series for high temp). Their “Shredder” pumps utilize tungsten carbide cutting tips against a suction plate to macerate solids before they enter the volute. This is distinct from a grinder pump; it is designed for higher flows and tougher solids.

Engineering Merit: BJM is specified when the fluid properties would destroy a standard cast iron or ductile iron pump. Examples include acidic wastewater bypasses or digester cleanouts where the temperature exceeds 140°F (60°C)—a temperature that causes standard submersible motor windings and seals to fail. BJM’s oil-filled motors and high-temp seal elastomers are engineered specifically for these hostile environments.

5. Application Fit Guidance

Matching the specific OEM strengths to the application is the consulting engineer’s primary responsibility. The following guidance aligns equipment categories with typical project profiles.

Municipal Sewer Bypass (Gravity Main Rehab)

Preferred OEMs: Godwin (Xylem), Thompson Pump
Reasoning: These projects typically involve suction lifts from manholes and variable flows. The vacuum/compressor-assisted priming systems of Godwin and Thompson are essential here to handle the “snore” conditions (mix of air and water) effectively without losing prime. The ability to run dry indefinitely is a key requirement.

Deep Lift Station Rehabilitation

Preferred OEMs: Tsurumi, Godwin (Submersible Line)
Reasoning: When the suction lift exceeds 25-28 feet, surface-mounted suction pumps are physically incapable of lifting the fluid due to vapor pressure limits. Submersible pumps are the only viable option. Tsurumi’s rugged design allows them to sit on the grit at the bottom of a wet well without immediate seal failure.

Industrial and Chemical Wastewater

Preferred OEMs: BJM Pumps, Thompson Pump (Stainless options)
Reasoning: Standard cast iron pumps will corrode rapidly in low pH (acidic) or high pH (caustic) environments. BJM’s 316SS series is the standard specification for chemical resistance. Thompson also offers stainless steel wet ends for their surface pumps.

Sludge Transfer and Digester Cleaning

Preferred OEMs: Gorman-Rupp, Godwin
Reasoning: These fluids are viscous and laden with solids. Gorman-Rupp’s large volute design and easy access for unclogging make it ideal for sludge that might plug a standard pump. Godwin’s positive displacement or high-head centrifugal options are also effective for moving dense sludge over long distances.

Mission-Critical / Unmanned Sites

Preferred OEMs: Godwin, Thompson Pump
Reasoning: For sites without 24/7 operator presence, telemetry is non-negotiable. Godwin’s Field Smart Technology and Thompson’s control panels provide the necessary remote visibility and alarming (fuel low, failure to start, high water) required to mitigate risk.

6. Engineer & Operator Considerations

Successful deployment of emergency bypass systems involves more than selecting the right brand. It requires careful attention to installation details and long-term support logistics.

Installation Best Practices

Suction Piping Integrity: The single most common cause of bypass failure is a vacuum leak on the suction side. Even a pinhole leak can prevent a vacuum-assisted pump from priming or reduce its capacity significantly. Engineers should specify fused HDPE pipe for suction lines whenever possible, or high-quality Bauer-style fittings with inspected O-rings.

Air Release Valves: In long discharge runs, air pockets can accumulate at high points, restricting flow and causing water hammer. Automatic air release valves must be installed at all high points in the temporary discharge piping.

Thrust Restraint: Temporary piping, especially flexible lay-flat hose, moves dynamically under pressure surges. Proper thrust blocking or staking of the discharge line is critical to prevent the pipe from whipping and causing injury or property damage.

Commissioning Risks

NPSH Calculations: A common engineering error is failing to calculate Net Positive Suction Head Available (NPSHa) for the specific temporary setup. Just because a pump can lift 25 feet doesn’t mean it can deliver full flow at that lift. As lift increases, capacity decreases and the risk of cavitation increases. Engineers must verify the pump curve against the actual physical elevation of the site.

Transducer Placement: For automated systems, the level transducer must be placed in a stilling well or a calm section of the wet well. Turbulence from the influent line can cause erratic readings, leading to rapid cycling (hunting) of the pump, which burns out starters and drains batteries.

Maintenance Access and Support

Spare Parts Strategy: For long-term bypass rentals or purchases, the availability of consumables is vital. This includes fuel filters, oil filters, mechanical seal kits, and vacuum pump vanes/oil. Godwin and Thompson have extensive distributor networks that typically stock these parts locally.

Fuel Logistics: A 6-inch diesel pump under full load can consume 4-6 gallons of diesel per hour. A standard tank might last 24 hours. Over a weekend, this requires scheduled fuel drops. Engineers must plan for fuel truck access to the site—if the pump is placed down a muddy easement, how will the fuel truck reach it?

7. Conclusion

The selection of Emergency Bypass and Temporary Pumping systems is a critical exercise in risk management for water and wastewater utilities. It demands equipment that balances hydraulic versatility with mechanical ruggedness. The market is defined by distinct engineering philosophies: the vacuum-assisted dominance of Godwin (Xylem) and Thompson Pump for general municipal bypass; the electric submersible durability of Tsurumi for deep and abrasive applications; the service-friendly self-priming designs of Gorman-Rupp for accessible, sludge-heavy applications; and the specialized severe-duty metallurgy of BJM Pumps for industrial challenges.

Consulting engineers and operations managers must look beyond the rental rate or the purchase price. The true cost of these systems is measured in reliability. A single sanitary sewer overflow caused by a pump failing to prime or a seal failure can cost more in regulatory fines and environmental cleanup than the entire capital cost of the equipment. Therefore, specifications must be rigorous, detailing priming capabilities, solids handling sizing, material construction, and automation requirements to ensure that when the permanent infrastructure goes offline, the temporary system performs with absolute certainty.

source https://www.waterandwastewater.com/top-oems-for-emergency-bypass-temporary-pumping-systems/