Jiangsu Haifa Machinery Manufacturing Co., Ltd.

When selecting pump sets for refining, coal chemical, salt chemical, and overseas Russian-standard projects, we often encounter a common on-site issue: the medium is located in underground pits, sumps, tanks, or low-level water tanks, with the pump room positioned above the liquid level. The user expects the equipment to reliably draw the medium up. If a long-shaft vertical submerged pump is used, later maintenance becomes very inconvenient. Due to limited on-site space, the user also does not want to add an external self-priming tank, vacuum buffer tank, or priming tank.

The traditional approach is to add a self-priming or vacuum priming device on the pump inlet pipeline. This solution works, but in applications such as coking cutting water, wastewater containing trace coke fines, oily wastewater, and corrosive media, external tanks and complex piping can introduce several issues: large footprint, multiple leakage points, easy accumulation of liquid and sediment in the pipeline, high maintenance workload, and a noticeable drop in self-priming capability if there is any air leak on-site.

We developed the horizontal self-priming without an external self-priming tank specifically to address these on-site pain points. It is not simply a standard centrifugal pump with an added tank; instead, the liquid storage chamber, return channel, and gas-liquid separation structure are integrated into the pump body, allowing the self-priming to occur internally. After the initial filling, subsequent starts and stops do not require manual re-priming, making it more suitable for intermittent start-stop operations, underground tank lifting, coking cutting water circulation, and chemical wastewater lifting.

1. Why We Eliminated the External Self-Priming Tank

From a maintenance perspective, more external self-priming tanks do necessarily mean greater reliability. Especially in refining units, the more complex the piping, the more flanges, valves and connections there are, increasing the risk of leakage and blockage over time.

This is particularly evident in coking water applications. The cutting water in delayed coking units often contains fine coke fines and slight oil contamination, meaning the medium is not particularly clean. If the self-priming tank piping remain in low-flow areas for extended periods, coke fines and contaminants can settle, potentially affecting self-priming stability over time. On-site maintenance, including cleaning the tank and piping, can also be cumbersome.

The concept behind the horizontal self-priming pump without an external tank is to integrate the previously external liquid storage and gas-liquid separation functions into the pump body as much possible, reducing external auxiliary equipment. The benefits include a more compact layout, simpler installation foundation, fewer on-site leakage points, and easier retrofitting of existing units.

2. Structural Features of the Horizontal Self-Priming Pump Without an External Tank

The core of this pump is not simply "removing one tank"; rather, the internal structure of the pump body be capable of completing liquid storage, mixing, separation, and exhaust circulation. In our structural design, focus on the following key:

1. First, a liquid storage chamber is set inside the pump body. After the initial filling, the pump body retains some liquid when stopped, providing self-priming conditions for the next start.

2. Second, a built-in gas-liquid separation structure is adopted. After startup, air from the suction line mixes with the liquid inside the pump, undergoes gas-liquid separation within the pump body, with air discharged through the outlet while the liquid continues circulating until the air in the suction line is gradually expelled.

3. Third the entire unit adopts a horizontal layout. This horizontal structure facilitates integrated installation with the motor, base, coupling, and guard, making on-site alignment and maintenance easier, and is also suitable for common pump room layouts in refining units.

4. Fourth, external self-priming tanks vacuum tanks, and complex priming pipelines are eliminated. This reduces footprint, connections, leakage points, and later maintenance difficulty.

5. Fifth, it is suitable for frequent start-stop operations. For applications such as underground tank liquid level lifting, emergency drainage, intermittent pumping, and coking cutting water recovery, the pump set often does not run continuously at full load but starts and stops based on liquid level or process rhythm. The built-in self-priming structure is better suited for this usage pattern.

3. Main Technical Parameters of the Product

The horizontal self-priming without an external tank can be selected based on the user's operating conditions. Common parameter ranges are as follows:

| Parameter Item | Technical Specification |
|----------------|------------------------|
| Pump Type Structure | Horizontal, built-in self-priming structure, no external self-priming tank |
| Flow Range | 5–3000 m³/h |
| Head Range |15–255 m |
| Self-Priming Height | 6–9 m; check on-site conditions to determine if a foot valve is needed |
| Valve | Usually not required; confirm based on suction line conditions |
| Medium Temperature | -20°C to 450C |
| Suitable Media | Coking cutting water, wastewater containing trace coke fines, oily circulating water, chemical acid/alkali media, general clean water |
| Flow-Wetted Materials | 304, 316L, 347, Hastelloy C-276, PTFE-lined options available |
| Motor Configuration | Standard motor, explosion-proof motor, variable-frequency motor, explosion-proof variable-frequency motor |
| Typical Applications | Underground tank lifting, tank suction, coking cutting water, chemical wastewater, low-level sump transfer |

4. Relationship with API610 Chemical Process Pumps

The horizontal self-priming pump without an external tank primarily addresses-level suction, underground tank lifting, intermittent liquid discharge, and self-priming transfer. In large refining and chemical projects, it often does not appear alone but works together with API610 chemical process to form a complete pump system.

Jiangsu Haifa has long produced API610 series chemical process pumps, including OH, BB, and VS types Different pump types suit different operating conditions:

| Pump Type | Common Structure and Application | Typical Parameter Range |
|-----------|----------------------------------|-------------------------|
| API610 OH1/OH2 HES Chemical Process Pump | Horizontal, radially split, single-stage overhung centrifugal pump, suitable for refining, petrochemical, coal chemical, chemical fiber, environmental protection, etc. | Flow 2–2600 m³/h, head up to 300 m, temperature -80–450°C, design pressure 2.5–26 MPa |
| API610 BB2 Heavy-Duty Petrochemical Process Pump | Horizontal, radially split, between-bearing support, suitable for harsh, high-temperature, high-pressure, continuous operation | Flow 50–4000 m/h, head up 650 m, temperature80–450°C, design pressure 5.015.0 MPa |
| API610 BB5 Doublease Barrel Multistage Centrifugal Pump | Horizontal multistage, high-pressure structure, suitable for hydrogenation, cracking, high-pressure circulation, high-pressure water injection, etc. | Flow –730 m³/h head up to 2800–3400 m, design pressure up to 30–35 MPa |
| API610 OH2-HES(X) Small-Flow Chemical Process Pump | Small flow, high head, suitable for clean or slightly particulate flammable, explosive, highly corrosive media | Flow 0.8–12.5 m³/h, head 12–125 m, temperature -80–450°C |

In refinery projects, if the main process requires high-temperature, high-pressure, continuous and stable transfer, we generally prioritize API610 OH, BB, and VS series pumps. For auxiliary conditions requiring self-priming capability, such as low-level tanks, sumps, wastewater pits, coking cutting water recovery, and ground tank drainage, the horizontal self-priming pump without an external tank can be considered. This combination meets the standardization requirements of main process pumps while solving on-site low-level suction and drainage issues.

5. Explosion-Proof Variable-Frequency Motor Configuration

Chemical and refining sites have strict requirements for motor configuration, especially in areas with flammable gases, oil vapor, or explosion-proof zones. It is not enough to only check motor power; protection level, explosion-proof rating, cooling method, and operating mode must also be suitable for the site.

The horizontal self-priming pump without an external tank can be equipped with an explosion-proof-frequency motor as per project requirements. Common configurations include:

1. Cooling Method: IC411 self-fan cooling

2. ection Level: IP65

3. ExplosionProof Rating: Ex db ⅡB T4 Gb (confirmable per project requirements)

Operating Mode: S1 continuous duty

1. Control Method: Can be paired with a variable-frequency control cabinet for liquid level interlocking, flow regulation, and energy-saving operation

For coking cutting water, wastewater lifting, and underground tank drainage conditions, variable-frequency control offers an advantage: it can adjust speed based on liquid level and actual flow, reducing the impact of frequent hard starts on the pump set, piping, and motor.

6. Suitable On-Site Operating Conditions

Based on the projects we have handled, the horizontal self-priming pump without an external tank is well-suited for the following scenarios:1. Delayed Coking Cutting Water Conditions  Coking cutting water may contain fine coke fines and slight oil contamination, with start-stop operations, significant liquid level fluctuations, and complex piping conditions. The absence of an external self-priming tank reduces the risk of sediment accumulation in external tanks and pipeline blockages, making maintenance more straightforward.2. Underground Tank and Low-Level Tank Lifting  In many chemical plants, liquid level in collection tanks, emergency tanks, wastewater tanks, and underground tanks is below the pump centerline, making it difficult for standard centrifugal pumps to start. The self-priming structure reduces the need for civil engineering modifications and pump pit excavation, making it suitable for retrofitting existing units.3. Corrosive Media Transfer  For acid/alkali liquids, salt chemical media, and corrosive wastewater, materials such as 304, 316L, 347, Hastelloy C-276, or PTFE-lined structures can be selected on the medium's properties. When selecting materials, we do not just look at the medium name; we also confirm concentration, temperature, chloride ion content, and the presence of particles or crystallization tendencies.4. Desulfurization, Denitrification, and Environmental Wastewater Systems  In desulfurization, denitrification, environmental wastewater, and solid-containing wastewater systems, some stations may not require large flow rates, but the media are complex with significant liquid level fluctuations.-priming pumps can used for low-level tank lifting, circulating liquid replenishment, drainage, and emergency pumping in auxiliary conditions.

7. Key Parameters We Focus on During Selection

When users inquire, providing only "flow, head, and medium name" is often insufficient. To ensure stable pump selection, we generally confirm the following:

1. Medium name, concentration, temperature, density, viscosity

2. Whether particles are present, particle size, content, and hardness

3. Whether oil is present, whether it is prone to crystallization or volatilization

4. Vertical height from the lowest liquid level to the pump centerline

5. Suction line length, diameter, number of elbows, and number of valves

6. Discharge line length, pressure requirements, and end equipment conditions

7. Whether explosion-proof motors, variable-frequency control, or liquid level interlocking are needed

8. Whether API610 pump matching, EAC certification documents, Russian documentation, or export packaging are required

9. Whether the site operates continuously, intermittently, or as emergency backup

10. Whether there are original pump models, on-site photos, foundation dimensions, and fault records

The more complete this information, the more accurate the selection. If a self-priming pump is selected only based on sample parameters, such as failure to prime, insufficient flow, excessive vibration, or abnormal motor load can easily occur on-site.

8. Frequently Asked Questions

Q1: Does the self-priming pump without a tank require no priming at all?  No. Before the first start, the pump body still needs to be filled with liquid. The difference is that after the initial filling, the pump retains some liquid, so subsequent starts and stops do not require repeated manual priming like standard centrifugal pumps.Q2: Will self-priming become unstable after removing the external tank?  Not necessarily. Stability depends on whether the internal liquid storage chamber, return channel, and gas-liquid separation structure are well-designed, as well as whether the on-site suction line has air leaks, the pipe diameter is appropriate, and the suction height is within the allowable range. We calculate suction conditions separately during selection.Q3: Will the pump clog if coking cutting water contains coke fines?  If the coke fines are trace and fine, the horizontal self-priming pump without an external tank can handle it. However, if the particle content is high, particle size is large, or medium contains long fibers or lumps, the flow passage, impeller structure, and material wear resistance need to be recalculated, and other wear-resistant pump types should be considered if necessary.Q4: Is this pump type classified as an API610 pump?  The horizontal self-priming pump without an external tank is mainly used for self-priming lifting and auxiliary transfer. Whether it follows API610 structure depends on the project technical agreement, pump type structure, and operating conditions. For high-temperature, high-pressure main process conditions in refining, we typically combine it with Jiangsu Haifa's API610 OH, BB, and VS series chemical process pumps for selection.

9. Our Technical Recommendations

If the site only involves clean water or short-term drainage, a standard self-priming pump may suffice. However, for conditions involving coking cutting water, chemical wastewater, corrosive media, underground tank lifting, frequent start-stop operations, explosion-proof areas, or overseas refinery projects, we recommend focusing not just on price, flow, and head, but also on structural reliability, conditions, materials, seals, motors, explosion-proof requirements, and later maintenance.

The value of the horizontal self-priming pump without an external tank lies in simplifying the system and reducing failure points. Removing one external self-priming tank means on-site footprint, one less section of piping, fewer flange connections, and less risk of later cleaning and air leaks.

Jiangsu Haifa Machinery Manufacturing Co., Ltd. can provide horizontal self-priming pumps without tanks, API610 chemical process pumps, explosion-proof variable-frequency pump sets, and supporting selection solutions for overseas refining projects based on user-provided medium parameters, on-site installation drawings, pump models, and issues. For coking cutting water, underground tank lifting, corrosive wastewater, and Russian/Central Asian refinery retrofit projects, we can offer comprehensive configurations from pump type structure, materials, seals, motors, certification documents, and on-site maintenance perspectives, helping users select more stable pumps and ensuring smoother later operation.

Jiangsu Haifa Machinery Manufacturing Co., Ltd.'s technical support originates from Jiangsu Ligong Group (founded in 195) and the Jingjiang Stainless Steel Pump and Valve Factory of the Central Iron and Steel Research Institute of the Ministry of Metallurgical Industry. We focus on the R&D and production of API610 chemical pumps, high-temperature and high-pressure pumps, coking-specific pumps, and overseas refinery supporting pumps, producing CQC Class 1 energy efficiency certified pumps.