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MART-GOFF Comparison

 

  DATE:

10 January 2003

  TO: MART Sales, Tech Service Staff, Production Manager, Plant Manager and QC Manager
  FROM: Gary Minkin, MART President/CEO
Technical review by Marc Treppler PE
  SUBJECT: In-House Report Comparison of GOFF HYDROPULSE and the MART Power Wash Process. This Report was originally created for internal Use by MART Staff
     
 

GOFF MARKETING CLAIMS: Goff claims that its Hydropulse Washing Machines, which utilize fluid slingers and control plates to produce energy and direct the wash solution towards the parts, will outperform washing machines that have pumps and nozzles. It also makes claims of superior reliability and lower maintenance. Quite simply, these claims are not accurate and Goff provides no data to support its claims.

The reality is that the slinger and control plate assembly described by Goff is, in fact, a very crude and inefficient pump. Further, Goff utilizes a centrifugal pump to move the wash solution from the reservoir to the slingers. Instead of nozzles to aim and control the solution, the slingers splash the solution onto moving control plates that generally direct the spray at the wash load.

Understand that pump design is a sophisticated science that is based on the Laws of Physics. For thousands of years engineers have relied on pump science and, over time, have developed sophisticated tools such as calculus and fluid flow equations to perfect pump designs.  None of this technology was employed by Goff, which is clear by the design and performance of its Hydropulse Washing Machines. For details of pump design and performance, review the Pump Technology article by Marc Treppler, Director of MART Engineering, here.

NOZZLE TECHNOLOGY: Goff claims that splashing wash solution on its control plate is an improvement over nozzles. Not so. Nozzles are precision devices that are engineered to maximize the performance of fluid delivery systems. MART uses state-of-the-art stainless steel nozzles that are machined to critical tolerances to precisely control the blast pattern distribution of the wash solution. Like pump systems, nozzle engineering is a science that addresses such issues as drop diameter averages, distribution, velocity profiles, transitional losses, spray angle vs distance, and flooding vs impact. Properly designed nozzles and their placement within the manifold system eliminate the striping of wash loads and ensure even overall coverage of the wash load surfaces.

The GOFF HYDROPULSE Slinger Wheel: Goff manufactures high quality steel shot blast systems. Like other shot blast manufacturers, Goff Shot Machines use slinger wheels to throw the shot at the parts load. The velocity of its most powerful Goff Shot Blast systems is reported to be 237 ft/sec.

Goff employs the same style shot Slinger Wheel in its Hydropulse Washing Machines. While a slinger wheel is an efficient means of delivering shot, it is wholly inefficient for moving fluids. The reason is that a fluid will always follow the path of least resistance and the slinger, which is a plate with rectangular tubes welded radially from the center hub to the perimeter, provides many opportunities for leakage and high efficiency losses.  The slinger disc is fed solution from a vertical pump.  Basically the slinger acts as a fluid distributor and breaks up the solid stream flow from the pump.  This is much like spraying a garden hose through a fan. The fan adds little if any energy to the water but acts to spray the water from the hose in every direction.  What is really curious about the Goff design is that no attempt is made to direct the solution out of the slinger in the direction of the desired path.  The fluid entering the slinger goes in every direction and only the solution that happens to exit in the direction of the parts is effective in washing.  The rest of the energy is wasted as it sprays against the walls of the cabinet.

While every carefully engineered device in the world has performance test data generated by the engineers who designed it, Goff provides no data on fluid flow, head pressure, impact pressure or efficiency of their slinger.  We can extrapolate some information from the details that is provided on its advertising literature. Goff claims the fluid movement at “70 miles per hour,” which is 103 feet per second. In other words, the slinger wheel that moves steel shot at 237 ft/sec only moves the wash solution at 103 feet per second. The velocity of the solids slinger drops by 57% when slinging solution. It does not make sense to estimate the efficiency of the Goff slinger because it adds no energy to the fluid.  Most of the hydraulic energy is provided by the pump system that feeds the solution into the slinger tubes through its vertical shaft.  Our engineers estimate that the slinger provides no more than 20% of its energy input to the fluid. With its three 5 horsepower motors (on the SRC machine) that total 15 horsepower of slinging input energy, the output energy from the slingers that is available for soil removal is equivalent to 3 horsepower.

To summarize the data prepared by our Engineering Department, the Goff Slinger Wheel rotates at 1,750 RPM, and delivers the combined flow and pressure from both slingers of 109 GPM at 72 PSI, with a velocity of 103 ft/sec.

We can compare this performance to the MART 7-1/2 horsepower Simplex Pump that delivers 139 GPM at 72 PSI, at a velocity of 103 ft/sec.  In other words, it takes three 5 HP Goff slingers, or 15 HP, to equal the flow, pressure and velocity of one 7-1/2 horsepower MART centrifugal pump.

Note also that Goff slingers are likely to require considerable service and repair.  The rubber flexible diaphragm that holds the slinger housing is subject to heat stress, and cracking and failure from the heat and chemical. The slinger will have bearings or bushings in the solution and these will wear as well. Further, a failed seal can flood the shop.

MART Pump Technology: MART offers the widest range of pumps in the industry for moderate to extremely tenacious soil removal. MART Pumps are the highest quality and most reliable in the industry. Simplex style Pumps are 7-1/2 to 40 horsepower.

MART pioneered and developed its Duplex (turbo) Pumps for applications that require higher performing pumps. Our larger Pump systems – 55 to 175 horsepower – are Duplex (turbo) Style, and our 110 horsepower and 140 horsepower Pumps are Quadroplex systems. MART Pump efficiencies run between 78% and 86% measured at the nozzle tips, which is the actual energy available for soil removal. This means that the energy at the nozzle tips from a 70 horsepower MART Duplex will be up to 60.2% greater than a 75 horsepower pump on any competitive washing machine. Our highest performing Pump systems blast over 640 GPM at 600 PSI impact pressure. The energy that is available for soil removal explains the difference between Power Washing and the Goff Hydropulse.

GOFF Control Plate in lieu of Nozzles: The Goff machine has no nozzles. Other than as a cost saving measure, we can find no other benefit to eliminating the nozzles. Instead of nozzles, the Goff “throws water in large waves” against an oscillating Control Plate that generally directs the solution towards the parts being washed. Note that, without nozzles there is no control of the spray distribution so that the solution moves in a random uncontrolled fashion against the wash load. Some parts surfaces in the Goff will be flooded without impact, and other surfaces will be missed completely and, therefore, will not come clean. Note that a wave pattern breaks up and loses impact pressure quickly when not controlled by nozzles. Furthermore, the slinger is located above the turntable and only sprays parts from the top down.  Any spray that reaches the bottom of the parts comes from solution that deflects off the cabinet walls and the floor.

MART Power Blast Manifold and Nozzles: MART invented and patented its Power Blast Manifold (PBM) technology in 1984. As you know, the PBM blasts from the top down, bottom upward, and across the cabinet. Instead of being stationary, the PBM pivots on its vertical axis, making a 46 degree forward and reverse sweep every ten seconds, throughout the wash cycle.  The wash load rotates on the Table, and the movement of the PBM is not synchronized to the Table speed so that all parts surfaces, even those deeply embedded and hidden, are exposed to blasted solution under pressure. MART uses a wide range of nozzles to optimize soil removal. Each cleaning application will have the nozzle configuration that is appropriate for the work. MART engineers determine the nozzle patterns and flow.

Our ability to make these adjustments is based on experimentation and the knowledge that MART has gained in the field over the past 34 years. This enables MART to meet its ultimate objective of helping Power Washer owners turn their cleaning burdens into profit centers.

   


 



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