15781 HUMIDIFIERS

PART 1 GENERAL

A. SCOPE

[Go to top of page]

1. Furnish and install as indicated on the drawings an in-duct atomizing humidification and evaporative cooling system complete with Controls Cabinets, Modulating Control Sections, and Atomizing Manifold Assembly. Note control cabinets and modulating control section may be supplied as one cabinetized U.L. approved assembly. 
2. Warranty system for a period of one year from date of startup. 
3. Provide owner's manual to cover installation, startup, operating and maintenance instructions. 
4. Water quality is essential to operation of unit. Complete water analysis to be provided to manufacturer for recommendations to enhance performance and minimize maintenance. 
5. Refer to schedule on drawings for capacities. 

PART 2 PRODUCT

A. CONTROL CABINET

[Go to top of page]

1. Factory fabricated and tested. 
2. All internal components prewired and prepared to terminals, ready for field connections. 
3. ON-OFF switch with "Power ON" lamp. 
4. Standalone systems provide supply and return air humidity readings. 
5. Relay for each stage of control allowing stages to be controlled in parallel or series. 
6. Controls to incorporate a clean-out cycle time to keep the heads clean and in working order. 
7. Optional - The system shall incorporate an automatic blow-down technique to empty the water lines of all liquid on shutdown to prevent freezing. 

B. MODULATING CONTROL SECTIONS

[Go to top of page]

1. Each humidification system shall consist of two control sections; one for compressed air supply and the other for modulating water supply. 
2. The water control section shall consist of a ball valve, pressure regulator with strainer, pressure gauges, water modulating valve (if used) and a solenoid valve(s). Water pressure to the control section shall be 50 psi and water pressure to duct manifold shall be maintained at 40 psi minimum. 
3. The air control section shall consist of a ball valve, pressure gauge, solenoid valve, pressure regulator with strainer, and an air pressure switch. Compressed air to the control section shall be 60 psi and air pressure to the duct manifold shall be maintained at 30 psi. 
4. If aggressive water is supplied, the water control section will be constructed of 300 series stainless steel components that resist degradation. 
5. All air & water piping shall be type "L" copper or stainless steel. 
6. Electrical requirements are 120 volt, single phase. Maximum amp draw will be 5 amps per control section. Other voltages are available. 

C. ATOMIZING HEAD MANIFOLD

[Go to top of page]

1. Manifold shall be factory assembled unit consisting of air and water piping and atomizing heads. Materials used will be based on water quality. 
2. Atomizing head capacity shall be (6), (8), (10), (12), (15) pounds of water per hour. Larger capacity heads will not be accepted. Heads will be positioned to provide the maximum possible distribution. 
3. Atomizing heads shall be of materials not adversely affected by the purity or aggressiveness of the water, easily disassembled for servicing with self-cleaning and purging feature to provide a complete drip-free operation. Average droplet size will not exceed 10 micron at 100% output and will decrease as the system modulates downward. Documentation of droplet size available on request. 
4. Atomizing heads will work on the internal mix method. 
5. External mix heads and heads with external appendages are not acceptable. 
6. Each head will not exceed 81 dBA when in operation. 
7. Single manifold systems to have full modulation with a 30:1 turndown ratio. Dual manifold systems to have full modulation on each stage. 
8. Air/water ratio will increase as the system modulates, which will reduce the droplet size. Increasing or constant air/water ratios on modulation will not be accepted. 
9. Manifold length shall be as indicated on the drawings or sized by the manufacturer to meet the calculated load. 
10. Air consumption shall be a maximum of 12 SCFM free air per 100 pounds of water atomized. Compressor shall include an appropriate safety factor. 

D. OPERATING SEQUENCE

[Go to top of page]

1. On a fall in relative humidity (in the space or return air duct), the space or return air transmitter shall send a signal to the controller. 
2. A discharge high limit controller shall supply a signal to the controller. 
3. The controller shall have an adjustable setpoint for both the return air (or space) and high limit, and shall compare the sensed relative humidity to the respective setpoints. 
4. The controller shall output a proportional signal based on the humidity input which is closest to its respective setpoint. 
5. On multi-manifold applications, the manifolds will be modulated in parallel or stages depending on the application. 
6. The system will automatically shutdown if the airflow switch, located in the discharge duct, is deactivated. 
7. A power failure or compressor failure will automatically shut the system down. 
8. If water pressure is lost or reduced, the atomizing heads shall sputter with no drippage. Complete loss of water supply will cause the atomizing heads to blow air only. 

PART 3 EXECUTION

A. GENERAL

[Go to top of page]

1. Install system(s) as detailed on the drawings and/or as recommended by the manufacturer. Shop drawings, indicating manifold sizes and atomizing head capabilities shall be provided by manufacturer. Certified independent air consumption (at various output levels) and noise data shall be available. 
2. Manufacturer's representative shall provide analysis, design and startup support of the custom engineered humidification system(s). 
3. System will be started by factory personnel. 
4. Compressed air shall be oil free and dry. Air shall be filtered to a maximum of 0.3 micron. Dryers and aftercoolers "applied" as the compressor manufacturer recommends. 
5. Water treatment, if supplied, demonstrates a satisfactory water supply to the humidifier.