Van Air Systems MHL3, MHL50 User Manual

Van Air Systems MHL-Series Desiccant Air Dryer Operations and Maintenance Manual

MHL-SERIES

HEATLESS DRYER

INSTALLATION, OPERATION &

MAINTENANCE MANUAL

October 2008

32-0296 Rev A

TABLE OF CONTENTS

SECTION 1 General Information: Pg 2 Model Numbers Serial Numbers Description of Operation

SECTION 2 Safety Instructions: Pg 3 Installation/Maintenance Safety Operation Safety

SECTION 3 Specifications: Pg 3 Dimensions & Weights Air Flow Capacities

SECTION 4 Installing the Dryer: Pg 4-6 Location Electrical Connections Piping and Connections Recommended Filters Recommended Dryer Installation

SECTION 5 Start-Up Procedure Pg 7 SECTION 6 Maintenance and Repair Pg 7 SECTION 7 Troubleshooting Guide Pg 8 SECTION 8 Replacement Parts Pg 9-10 SECTION 9 Wiring Diagram Pg 11 SECTION 10 Warranty Pg 11

Page 1

Van Air Systems MHL-Series Desiccant Air Dryer Operations and Maintenance Manual

SECTION 1 GENERAL INFORMATION

1.1 MODEL NUMBER CODING

Indicator are standard equipment.

Note: Tower Pressure Gauges & outlet Moisture

1.2 SERIAL NUMBER CODING

MONTH/YEAR OF MANUFACTURE

1.3 DESCRIPTION OF OPERATION

The MHL-SERIES Air Dryers use the pressure swing adsorption method of drying compressed air. This requires two identical towers containing beds of hygroscopic desiccant.

Incoming wet air enters the dryer through a shuttle valve where it is directed to the bottom of the tower containing dry desiccant. The desiccant in this tower removes 99.7+% of the water vapor from the air when operated at catalog conditions. The dried air leaving the top of the tower is directed to the outlet through a second shuttle valve. In this outlet shuttle valve a built-in orifice allows a portion of the dried air to flow into the other tower being regenerated. The orifice reduces the high pressure air down close to atmospheric pressure which lowers the dew point of the dried air even further.

The tower being regenerated/purged of moisture is connected to an energized solenoid valve for a controlled period of time. The electrical signal to the solenoid is monitored by an LED light on the solid state timer. After the desiccant is regenerated, the timer deenergizes the solenoid valve. Air continues to flow through the orifice to repressurize the regenerated tower to line pressure. The middle light on the timer indicates the repressurization function.

Next, the timer opens the valve on the tower containing the wet desiccant. This shifts the shuttle valves, and the tower with the wet desiccant is regenerated while the other tower continues to dry the air. Examining the flow schematic to the right demonstrates the dryer process operation.

TOWER T

DRYING

INLET AIR

VALVE V

CLOSED

SERIAL #

DRY OUTLET AIR

WET INLET AIR

SHUTTLE VALVE

WITH

FIXED ORIFICE

TOWER T

REGENERATING

(PURGING)

VALVE V

OPEN

Page 2

Van Air Systems MHL-Series Desiccant Air Dryer Operations and Maintenance Manual

MTG

SECTION 2 SAFETY INSTRUCTIONS

2.1 INSTALLATION/MAINTENANCE SAFETY

Before starting or installing the dryer, be sure that all power to the unit is off, valves are shut, and the air circuit is at atmospheric pressure. DO NOT remove, repair, or replace any component, control filter, or part, while the air circuit is energized or under pressure. Turn off the main to the dryer and de-pressurize the unit before starting installation or maintenance procedures.

MANUFACTURER WILL NOT BE RESPONSIBLE FOR DAMAGE TO EQUIPMENT AS A RESULT OF IMPROPER WIRING OR ELECTRICAL INSTALLATION. IT IS THE CUSTOMERS RESPONSIBILITY TO ENSURE THAT THE ELECTRICAL INSTALLATION IS CORRECT AND UP TO APPLICABLE CODES.

When installing the dryer, ensure that the NEMA rating of the control box is applicable to the installation.

Dryer is rated NEMA 4.

2.2 OPERATION SAFETY

DO NOT OPERATE THE DRYER ABOVE THE STATED WORKING PRESSURE (SEE SPECIFICATION TABLE). FAILURE, INJURY AND EQUIPMENT DAMAGE COULD RESULT.

EXCEPT as otherwise specified by the manufacturer, this product is specifically designed for compressed air service and use with any other gas or liquid is a misapplication. Use with or injection of certain hazardous liquids or gases in the system (i.e., alcohol or liquid petroleum gas) could be harmful to the unit and result in a combustible condition or cause hazardous external leakage. Manufacturer’s warranties are void in the event of a misapplication and manufacturer assumes NO RESPONSIBILITY for any resulting loss. Before using equipment with fluids or gases other than air, or for non-industrial applications, consult Van Air Systems for written approval.

SECTION 3 SPECIFICATIONS

3.1 DIMENSIONS & WEIGHTS

MODEL

H W D P A B

PORTS

(npt)

MHL3 MHL6

13.6 7.4 5.2 9.3 5.8 2.8 3/8

18.2 7.4 5.2 13.0 5.8 2.8 3/8

HOLE

DIA.

0.3

WEIGHT

(lbs)

MHL9 MHL12 MHL16 MHL25 MHL35

17.3 7.4 5.2 12.1 5.8 2.8 3/8

20.1 7.4 5.2 14.9 5.8 2.8 3/8

33.0 9.5 6.5 20.7 7.0 23.6 1/2

41.9 9.5 6.5 29.5 7.0 32.5 1/2

39.3 10.0 7.0 26.5 9.0 30.1 1/2

0.3

0.4

MHL50

NOTE: MHL16-MHL35 dryer shown with bracket top and bottom. MHL3-MHL12 has single 4-hole bracket.

Maximum Working Pressure: 150 PSIG Maximum Ambient Temperature: 120° F

47.4 10.0 7.0 33.5 9.0 37.1 1/2

Dimensions shown in inches.

3.2 AIR FLOW CAPACITIES

0.4

CAUTION:

FLOW MULTIPLIERS FOR VARIOUS PRESSURES

PRESSURE 80 90 100 110 120 MULTIPLIER 0.683 0.833 1.000 1.087 1.174

Page 3

Van Air Systems MHL-Series Desiccant Air Dryer Operations and Maintenance Manual

SECTION 4 INSTALLING THE DRYER

4.1 LOCATION

DO NOT INSTALL DRYER IN AN ENVIRONMENT OF CORROSIVE CHEMICALS, EXPLOSIVE GASES, OR AREAS OF HIGH AMBIENT TEMPERATURE CONDITIONS.

Install the dryer indoors. Dryers are not meant to be installed outdoors exposed to the weather. If the dryer must be installed outdoors, it must be in a weatherproof enclosure that provides for proper temperature control.

When mounting, allow 2.5 inches above unit for tower removal and replacement.

The dryer may be installed in a vertical or horizontal (laying flat) orientation. Installation on its side may contribute to possible shuttle valve shifting problems.

4.2 ELECTRICAL CONNECTIONS

Before wiring, check the dryer nameplate for electrical characteristics. Standard electrical characteristics are 115 volt, 1 phase, 50/60 Hz. Models operating on 230 volts are available.

IMPORTANT! No overload protection is provided in the dryer and unit should be wired into a protected circuit.

IMPORTANT! When installing electrical service to this machine, comply with the National Electrical Code as well as state and local building codes.

NOTE: Dryer cycle timer has infinite memory capacity. Dryer may be wired to compressor pressure switch or auxiliary contacts to allow dryer to start and stop with compressor or machine tool. Contacts must supply same voltage and phase as dryer requires.

A six foot power cord is installed as standard on the dryer. The cord on the115V dryers has a plug. The cord on the 230V dryers does not have a plug. The control box and bulkhead fittings are NEMA 4 rated.

• If a NEMA 1 installation is desired:

A. You may simply plug the power cord into a standard outlet.

- or -

B. Use standard flexible conduit, and follow the

instructions for installing liquid-tight conduit below. Use only flexible conduit as installing rigid conduit may damage polycarbonate control box. Connect to inlet power terminal strip with 18 gauge stranded wire only.

• If maintaining the NEMA 4 installation is desired:

A. Cut off the plug and use a NEMA 4 gasketed

bulkhead fitting suitable for .180” diameter power cord to enter a NEMA 4 rated junction box.

- or -

A. To use flexible liquid-tight conduit and stranded 18

gauge wire:

1. Remove clear cover from control box.

2. Loosen nuts on (3) bulkhead connectors and push an inch or two of each of the electrical cords back into the control box to allow slack to pull out solid state timer board. Remove four screws holding solid state timer board and pull back gently to expose the “power in” terminal block. With small screwdriver, loosen wire clamps on terminal block and disconnect power cord wires.

3. Remove (1) backing nut from inlet power cord bulkhead fitting and remove power cord and bulkhead fitting.

4. Enlarge existing hole to proper size to install your own liquid-tight conduit fitting. Use only flexible liquid-tight conduit as installing rigid conduit may damage polycarbonate control box.

5. Connect to “power in” terminal block with 18 gauge stranded wire only.

BACK SIDE OF TIMER BOARD

POWER IN

TERMINAL BLOCK

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