Asynchronous and Synchronous Wanner™ Hydra-Cell^® Pro Pump Designs

 

 

Since 1972 Wanner Engineering manufactures sealless positive displacement pumps capable of high pressures (maximum of 1,000-5,000 PSIG depending upon pump model). The initial Wanner™ Hydra-Cell^® pump design patented in 1972 was based upon a synchronous hydraulic piston design and it wasn’t until 2009 that Wanner Engineering introduced higher flow rate and pressure versions of their Wanner™ Hydra-Cell^® pumps based upon an asynchronous design. This article describes the difference between the synchronous and asynchronous Wanner™ Hydra-Cell^® Pro pump designs from the standpoint of clarifying how the asynchronous differs mechanically; this article is written for our customers which are familiar with the original synchronous design as originally patented in 1972 and still supplied today for the 20/03/04/10/12/15/17/25/35/40 and 66 pump models. It will also provide some insight into pros and cons of the synchronous and asynchronous designs.

The basic operating principle is the same, as the wobble plate or camshaft rotates, the Hydra-Cell forms a hydraulic piston which moves forward, flexes the diaphragm and displaces the process liquid from the pump chamber through the outlet check valve. With the exception of the 20 series single diaphragm design, the pumping process involves 3 to 5 diaphragms operating in series resulting in a smooth flow rate. The only seal is the static seal of the diaphragm circumference, thus mechanical seals, cups and packing are not required, eliminating those leakage pathways and enabling Hydra-Cell Pro pumps to reliably pump continuously even with the most difficult liquids.

Synchronous Design
This refers to the direct interaction of the mechanical driving force (wobble plate or camshaft) and the Hydra-Cell piston. The angle incorporated into the angled wobble plate or camshaft mechanically compresses the Hydra-Cell Pro check valve assembly responsible for generation of the fast-acting hydraulic piston. All Hydra-Cell Pro valves are responding in specific sequence as the pump shaft rotates.

 

 

The synchronous design requires less oil to create and regulate the hydraulic piston when compared to the asynchronous design. The integration of mechanical action results in precise displacement rates even under varying pressure conditions.

 

 

Asynchronous Design
This design is used in the T60/100/200 and Q155/330 series pumps where the oil flow acts as a more independent intermediary in the asynchronous system, enabling flexibility, rather than a mechanical linkage driving the piston directly. The camshaft drives the hydraulic piston, which creates pressure that acts on the oil to move the diaphragms. It’s not just routing oil; it’s about the hydraulic action of the piston pressurizing the oil to flex the diaphragms. The most accurate way of describing the asynchronous design is that the Hydra-Cell Pro valve is not a single assembly being acted upon mechanically, rather its components are separated and specifically decoupled from the mechanical driving force of the camshaft.

As previously mentioned, this design requires more hydraulic oil because the Hydra-Cell Pro valve is sort of spread-out, however the non-mechanical linkage aspect means that the oil also acts as a buffer between camshaft piston and Hydra-Cell Pro valve (eliminates the metal-to-metal interface). It also allows for smoother diaphragm motion and is essential to handle higher pressures and flow rates more reliably.

 

 

Another benefit to the “decoupled” asynchronous design is that it distributes the mechanical load more efficiently than the synchronous design which can face higher mechanical wear at extreme pressures, specifically because its pistons move in direct synchronization, causing more strain on individual components.

Not to be confused with the volume displaced, the asynchronous design responds quicker to pressure variations precisely because each hydraulic piston is “decoupled” from the mechanical driving force. This contributes to better accuracy at higher flow rates and is why this design is used for flow rates ≥60 GPM.

The added complexity of the asynchronous design does require slightly more components; comparing the D66 (synchronous, up to 65 GPM @ 1000 PSI, 63 components) to the T60 (asynchronous, up to 94 GPM @ 1000 PSI, 77 components)

Asynchronous pumps require more frequent oil changes due to their operation at higher pressures and greater dependence on hydraulic oil to regulate pressure across diaphragms. This greater oil usage also leads to higher temperature and faster oil degradation.

The asynchronous design relies on maintaining dynamic oil pressure for piston action, limiting its ability to operate at very low RPMs, thus the synchronous designs are used for low flow rates and higher turndown ratios due to the direct mechanical actuation of the pistons, making it better suited for low and even fractional RPM operation.

We have had customers maintain a pressurized line for instant pressure demand applications operating the 10/25/35 series pumps at fractional RPM simply to make-up for hydraulic losses.

Why? In the case of wash-down systems in food processing plants, operating Hydra-Cell Pro pumps in this manner saves significant energy by maintaining pressure in the system when it is not being used heavily and instantly ramping-up the pump RPM during usage. The less energy efficient and conventional method is to operate pumps continuously, bypassing pumped water to the feed tank to maintain line pressure. In a 2 or 3-shift operation typically 1 shift uses washdown stations frequently (requires high flow rate and pressure) whereas the other shifts have infrequent requirements (thus requires less flow at high pressure).

A synchronous design Hydra-Cell Pro pump, without the need for maintaining lubricated seals, is relatively unique in its ability to maintain pressure at nearly an infinite turndown ratio; The turndown limitation isn’t the pump, but rather the motor’s ability to cool and maintain shaft torque at an extremely low RPM.

The functionality and benefit of the sealless Hydra-Cell Pro pump design applies to both synchronous and asynchronous designs. While there are mechanical differences pertaining to the formation of the hydraulic piston driving the diaphragms, smooth and reliable performance is the dominate characteristic for all Hydra-Cell Pro pump models.

 

Summary of Pumping Action and Performance Comparison:

1. Pumping Action:

   • In the synchronous design, all diaphragms are tightly coupled to the camshaft or wobble plate through the in-line hydraulic pistons. This means that all diaphragms move together in a synchronized manner.

   • In the asynchronous design, the diaphragms move more independently because the hydraulic pistons are off-set, allowing for more fluid flexibility and reducing pulsation effects.

2. Performance:

   • The synchronous design tends to offer more precise flow at lower pressures and flow rates due to its direct mechanical linkage.

   • The asynchronous design shines at higher pressures and flow rates, where the independent diaphragm motion allows for smoother operation and less mechanical stress.

3. Reliability: Synchronous designs may face higher mechanical wear at extreme pressures due to the direct coupling of the pistons, while asynchronous designs are generally more reliable under higher loads due to their distributed motion and flexibility.