WP9

Overview

The Hobart WP9 is a waterpress for a commercial pulper waste system. It receives slurry, presses out water, sends return water back to the pulper for reuse and discharges semi-dry pulp. Hobart states that the waterpress reduces waste volume by up to 88%. The manufacturer lists it for foodservice waste in schools, hospitals, clubs, quick-service operations, commercial restaurants, commissaries and airline kitchens; it is also suitable for confidential document destruction.

The WP9 is identified in the WPR1200 WastePro installation and operation manual as one of the waterpress models that can be used with the waste system. The manual describes the complete system, including the pulper, piping and controls; system-level operating details below are identified as such.

Key Features

• Pressing assembly: A 9-inch-diameter, gear-driven helical screw with an attached nylon brush operates inside a perforated cylindrical screen.
• Moisture control: Stainless steel wiper plates control the moisture content of discharged pulp.
• Water recovery: The waterpress squeezes slurry and returns process water to the pulper for reuse.
• Service access: The screw and screen assembly can be removed without disconnecting the slurry or return-water piping. A removable stainless steel access cover and access door support cleaning and maintenance.
• Construction: The waterpress assembly has a stainless steel shell, screen and screw. The stainless steel discharge housing contains the gear reducer and discharge chute.
• System controls: The standard control panel is prewired and field mounted. Interlocks prevent operation, or stop operation, if the waterpress discharge-chute cover is raised.

Specifications

• Model: WP-9 Waterpress.
• Pressing screw: 9-inch-diameter, gear-driven helical screw with attached nylon brush.
• Waterpress motor: 5 H.P.; foot mounted, totally enclosed and fan cooled.
• Return-pump motor: 5 H.P. standard; heavy duty, foot mounted, totally enclosed and fan cooled. Other horsepower is available, according to the manufacturer.
• Return-pump set: Includes the motor, a stainless steel impeller and a mechanical seal to protect the stainless steel drive shaft.
• Assembly: Stainless steel shell, screw, screen, wiper plates and access cover; includes slurry inlet, return-water outlet and overflow connections.
• Discharge housing: Stainless steel, with gear reducer and stainless steel discharge chute.
• Base: Tubular steel structural members with stainless steel flanged feet; supports the waterpress assembly, discharge housing and return-pump set.
• Valves: Motorized and manual 1 1/2-inch NPT ball valves for system pump-down; field mounted.
• Control panel: UL508 listed industrial control panel, prewired in a NEMA 4 stainless steel enclosure and field mounted. The panel includes a main circuit breaker interlocked with the door handle, nominal 115-volt controls, circuit breakers, magnetic starters and individual three-leg thermal overload protection for each motor.
• Electrical supply options: 200/60/3, 230/60/3 or 460/60/3, as listed by Hobart.
• Standard feature: Chemical pump.
• Options: Chute extension for through-wall discharge, auxiliary base to elevate the waterpress, heated chute, flush-mounted control panel, bus communication and pulp-level detection.

Installation & Requirements

Installation must follow the equipment drawings and applicable plumbing, sanitary and safety codes. The manual calls for the waste system to be located near a floor drain. Keep the floor drain or floor sink clear of, but accessible to, the unit; the manual specifies a 6-inch minimum subject to local code requirements. The customer provides the interconnecting slurry and return piping between the waterpress and pulper, as well as overflow and drain lines to a floor sink or floor drain. The manual specifies pressure-rated drainage fittings and says not to apply external strain to Hobart equipment. Protect equipment and piping from freezing and condensation.

For the WP9 waterpress fresh-water connection, connect hot water to the manual shutoff valve on the piping assembly at the side of the waterpress. The manual lists a 3/4-inch NPT valve size for the WP9 and requires incoming water pressure of 25 to 45 psig while flowing. Install a 1 1/2-inch pipe from the waterpress auto-rinse drain on the return piping assembly to a suitable floor drain. Use an open connection: do not make a direct plumbing connection or reduce the pipe size. Install the pulper drain with 2-inch pipe to a suitable floor drain using an open connection, without reducing the pipe size.

For slurry and return lines, follow the installation and piping drawings and pressure-test the completed piping system for leaks at 150 psig. The manual specifies standard Type M copper piping, accessible cleanouts at turns and every 50 feet of straight pipe, and long-radius T-Y or lateral fittings and 45-degree elbows. It warns against 90-degree elbows and right-angle turns because they can cause jams, and advises avoiding abrupt elevation changes that could cause airlocks. Terminate slurry and return lines with union or flanged fittings. Where a feed trough is used, its piping must run uphill to the trough connection.

Check the electrical service against the machine data plate before installation. Hobart lists the WP9 supply options as 200/60/3, 230/60/3 and 460/60/3. The manual requires electrical equipment to be grounded. The prewired panels, operator devices and electric valves are furnished with the system; the manual calls for a 1 1/4-inch watertight conduit between the wall-mounted control box and the machine control box, with motor and control wiring routed through it. A 3/8-inch air line also runs in this conduit. Remote push-button stations and their mounting brackets are installed by others. The manual does not specify a gas connection or ventilation requirement.

Operation

The following controls and feeding directions apply to the WPR1200 waste system described in the manual, which includes the pulper and WP9 waterpress. Before starting, close the pulper drain valve, turn the wall-mounted main power switch on and unlock the STOP button. Confirm that the pulper cover is closed, the waterpress door is in place and the discharge-chute cover is lowered. Set the Empty/Run switch to RUN. The system fills with water; when it reaches the proper level, the green Ready light on the Start button illuminates. Press START and wait for a continuous return-water flow before feeding waste.

Feed waste continuously and uniformly. The manual says the feed rate should not exceed 60 pounds in a three-minute period; overfeeding reduces the system’s rated operating capacity. Open large plastic bags before feeding and feed them one at a time, since unopened bags can fill with air and float. A sharp drop in return-water flow indicates the pulper may be overloaded; stop feeding until normal flow resumes. Avoid feeding a large amount of greasy swill at once, or overloading the pulper with bread or pastry. Mix these materials with bulky waste such as paper or corrugated boxes. The manual notes that contaminants in water and some waste materials, including glue in corrugated cardboard, can cause foaming; a defoaming agent may be used, with advice from the chemical supplier.

For shutdown, with the pulper running, turn the selector to EMPTY and let the shutdown timer complete; do not add waste during this cycle. Press STOP and engage its locking attachment, switch off power at the remote control box and open the drain valve before cleaning or maintenance. The manual recommends draining dirty water after each meal cycle and says the waste receptacle should not be taller than the bottom of the discharge chute. Empty it as needed.

Cleaning & Maintenance

The manual calls for regular daily cleaning. Follow the shutdown procedure, disconnect power at the main control box, tag the disconnect to show work is being performed and wait for the pulper disk to stop completely before cleaning. Keep hands out of the pulper and do not operate the system unless the required pulper-cover and waterpress discharge-chute interlocks are in place and functioning.

Remove non-pulpable material from the pulper tank, taking care around possible glass or other sharp items. Wash the tank interior with a hose, suitable brush, detergent and deodorant or another cleaning solution; clean the underside of the upper shell flange. Use water at 25 to 45 psig to wash the waterpress screen and interior walls of the waterpress and pulper tank. The manual recommends a long-handled nylon-bristle brush and cautions against spraying the chemical pump. Wipe down the exterior, clean the surrounding floor, close the drain valve and replace removed parts. It is not necessary to dig out the plug of pulp remaining at the top of the waterpress screw after cleaning.

Troubleshooting

• System will not start: The manual lists a tripped power-supply circuit breaker, the main control-box handle being OFF, a pulper cover or discharge-chute lid out of position, insufficient water, or a tripped overload as possible causes. Reset a tripped breaker or overload; turn the power handle ON; check the covers and lid; and check the water supply and drain valve.
• No water or insufficient make-up water: Check whether the water supply is off or the drain valve is open or leaking. Turn on the supply and close the drain valve; repair a leaking valve.
• Pulper jammed: The manual identifies overloading or scrap metal or heavy material jamming the pulping disc. Turn the machine off at the main control panel and clear the material. Call service if it cannot be removed.
• Waterpress jammed: Check for an obstructed discharge-chute outlet, hardened waste in the waterpress or a full trash container causing pulp to back up. Turn the machine off at the main control panel, clear the obstruction or hardened material, and empty the container.
• Slow or failed draining: The manual lists unprocessed material in the pulper or a clogged drain. Run the pulper to process material; if it will not process, turn off the machine and clean out the tank. Use water pressure to clear a drain clog.
• Excessive foaming: Certain materials, including glossy paper, cardboard and potatoes, can contribute to foaming. The manual advises adding a defoaming agent; it also lists draining and refilling the machine as a response.

Applications

Hobart lists the WP9 waterpress for foodservice waste systems in schools, hospitals, clubs, quick-service restaurants, commercial restaurants, commissaries and airline-in-flight kitchens. The manufacturer also identifies confidential document destruction as an application. In a waste system, the WP9 presses pulper slurry, recovers water for reuse and discharges semi-dry pulp.