Iowa Department of Transportation
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Recommended Modifications to Specifications for a Standard Prewet System

Prewet System

Spec. No. 32-A-0899

SPECIFICATIONS
for
140 GALLON TAILGATE MOUNTED PRE-WETTER

1.GENERAL

  1. Pre-wetter will be used to apply liquid ice control material onto granular material at the spreader spinner.
  2. Pump system should have a design rating of 4 GPM @ 1725 RPM.
  3. Tank shall be of a trapezoidal shape with a 140 US gallon capacity.
  4. System must be fully tested and calibrated to a 10 gallon per ton rate upon delivery to the Department. System shall be flushed and winterized with a suitable antifreeze solution to prevent freeze damage.
  5. All components, parts, pieces, fasteners, etc., shall be manufactured for nonferrous/non-rusting materials.
  6. Liquid ice control material hoses shall be 1/2 inch polyester braid reinforced clear PVC, suitable for cold weather use.
  7. All hoses and cables shall be long enough to allow the dump body tailgate to open for dumping over the spreader.

2.TANK

  1. Tank shall be purpose designed to fit a Department snow removal truck tailgate in the open spreader charging position. When installed it shall square-off the rear of the truck to a point even with the back of the installed spreader.
  2. Trapezoidal tank shall be approximately 19 inches wide at the top and 10 inches at the bottom. Height shall be 29 inches, overall length shall be 80 inches.
  3. Tank shall be constructed from rotationally molded UV stabilized polyethylene dyed opaque orange. It shall have a minimum average wall thickness of 0.400 inch. Design liquid rating of shall be a minimum of 14.5 Ibs. per gallon.
  4. There shall be three molded-in stiffeners, each approximately 6 inches wide, evenly spaced in the tank length.
  5. Gallon markings shall be molded into the right rear face of the tank directly above the sump where the "pump-fill" connector will be installed.
  6. Tank shall have a top center mounted 12-inch fill lid. Lid shall be tethered.
  7. A 4" x 8" x 6" sump shall be molded into the right side bottom. Sump shall have three molded-in female 1-1/4" NPT threaded ports.
  8. A suitable recess compartment shall be molded into the right tank end, large enough to hold the integral board mounted pumping system. Stainless steel bosses shall be molded into the tank to allow the entire pump system to be securely bolted into place, employing stainless steel bolts.
  9. Additional stainless steel bolt bosses shall be molded into the right end to allow the installation of a stainless steel cover door over the pump system to protect it. Cover shall have a full-length vertical stainless steel piano hinge bolted into the molded-in bosses down one side. The opposite side shall latch using two stainless steel thumbscrews threading into two of the molded-in bosses. Entire cover shall be easily removed.

3. FITTINGS

  1. The left rear facing port shall have a 1-1/4 NPT plug screwed into it. It shall be for quick draining or clean out of the tank.
  2. The left port shall have a serviceable "Y-type" mesh strainer plumber in so all anti-icing material pumped on via the bulk fill must pass through it.
  3. Right port shall have a 1-1/4 inch three-way ball valve installed to allow bulk fill, shutoff or suction to be selected. A 1-1/2 inch male cam-lock connector shall be installed to allow bulk filling A matching cam-lock cover cap shall be provided.
  4. A 3/4-inch 2-way valve shall be installed into the suction plumbing. When this valve is closed, normal flow of the anti-ice material shall occur. When the 3-way valve is turned to the closed position and this valve opened, flush material shall be sucked into the plumbing and pumping system, thoroughly displacing all corrosive materials. An approximate 12-inch hose piece shall be attached to this fitting to allow easy flush material introduction via a plastic jug.

4. PUMP SYSTEM WITH FLOW METER

  1. Material pump shall be a solid brass gear type, direct coupled to the hydraulic motor that will power the pre-wetter.
  2. Pre-wetter hydraulic system shall obtain its flow from the exhaust oil of the spreader auger motor circuit. Auger oil shall flow to a flow control valve, which will divert oil either to the hydraulic motor or back into the return oil circuit. Flow control must limit the oil flow so the pump never exceeds the design maximum RPM.
  3. Flow control shall be electrically controlled by the Raven spreader control in the truck cab, allowing precise metering of the oil flow.
  4. Pump system shall incorporate a calibrated Raven model RFM15 turbine style flow meter. Flow meter signal shall be sent to the spreader control, allowing a precise ground oriented liquid application rate. Rate shall be adjustable up to the limits of the pump design output.

5. MOUNTING SYSTEM

  1. Pre-wet system shall attach to the dump body tailgate via a full stainless steel framework. Frame shall fully support the tank with three main hangar brackets.
  2. Framework shall be fully adjustable, allowing the system to be mounted on most tailgate type and designs under standard production.
  3. Polyethylene tank shall be retained in the stainless steel mounting cradle with three 2-1/2 inch wide UV stabilized nylon tie down straps. Straps shall have a heavy duty threaded t-bolt mount on each end. Bolts shall pass through the mounting framework and be tension adjustable with stainless nuts.

6. NOZZLE DELIVERY SYSTEM

  1. Pre-wet liquid shall travel from the pump out to be applied on the spreader spinner.
  2. Two brass nozzles, each rated 1.0.GPM flow shall be mounted onto a bracket, attached to the spreader spinner with stainless bolt. Nozzles shall be directed to spray on the centerline of the spinner.
  3. A suitable cam-lock style quick connector shall be installed in the delivery line running to the nozzles. It shall be positioned in the line to approximately correspond to where the hydraulic quick connectors for the spinner assembly are, allowing the entire spinner assembly to be easily removed with the nozzle bracket assembly attached.
  4. A one-way check valve must be installed in the delivery line directly before the nozzles to prevent line drain down when the system is shut-off.

Maintained by Sheri R. Anderson
Last Updated: 06/29/06

 
 
 
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