Technical Specifications of Dehumidifier

The specifications of Dehumidifier covers design, manufacture, inspection, testing at works, packing and commissioning of dehumidifier units. The equipment shall conform in all respects to the specifications and meet all statutory requirements as well as perform continuous commercial operation.

General Terms :

• The dehumidifier shall be capable of sustained operation of either process or reactivation fan without energized react heat for prolonged periods of operation without damage to the humidity transfer media or bed contactor.

• The dehumidifier shall consist of a high efficiency desiccant rotor/bed. It shall have positive sealing of process and reactivation air streams to allow for independent airflow with no balancing required. The dehumidifier shall be fully automatic, factory assembled package unit, complete with reactivation heaters, filters, motors, fans, desiccant bed drive assembly, access panels, volume dampers, weather-proof or dust-tight automatic electrical panel, desiccant rotor/bed, and all component auxiliaries as recommended by the manufacturer for safe, unattended, automatic operation.
• The dehumidifier shall not require field piping, desiccant charging, pneumatics, or field erection of fans unless specifically requested by the Client.
• The unit casing construction shall have double skin to allow access without damaging the installation. The framework shall be of anodized extruded aluminum hollow sections in thermal break profile. The frame shall be assembled using pressure die cast aluminum joints to make a sturdy, strong and self-supporting frame work for various sections. Construction should be such that inner skin is isolated from outer skin by insulation and condensation on outside skin is avoided completely.

Double skin panels shall be 43mm thick fabricated out of best quality pre-plasticized 0.8mm GSS on outer side and plane 0.8mm Galvanized sheet form outside. The panels shall be fixed on aluminum extruded sections in such a manner that fixing screw head does not project on outer face on the panel and sharp end of the screw does not project inside the unit through double walled rib. The screw hole on panel will be blocked with nylon sleeve with cap. The panels shall be sealed to the framework by heavy duty ‘O’ ring gaskets held captive in the framed extrusion.

Panels shall be assembled together to form an enclosure that is capable of low air leakage potential, conforming to class A of EN 1886.

Details of the Desiccant rotor:

• The dehumidifier unit casing shall be compact and space saving in design, and, for ease of service and inspection, shall have test points for air pressure and air flow measurement. An observation window shall be provided to permit visual inspection of the bed while the unit is in operation.
• The desiccant material shall be adsorbent silica gel, non-toxic, non-flammable with no asbestos in desiccant media or desiccant rotor. It shall have long life with adequate air filtration. Each unit shall be equipped with a positive drive arrangement to insure slip free rotation at an adjustable rate of speed.
• The active desiccant material shall be at least 80% of the media weight, so as to ensure high performance and minimal heat carry over.
• The net organics in the honeycomb media shall not exceed 2%.
• The desiccant rotor shall have integral long life bearings supported by a simple fixed shaft design to allow a simple slide out of the rotor/bed.
• The desiccant media shall have a perimeter flange which should encircle the entire perimeter so as to allow greater durability and to roll the rotor on the ground, without damage. The perimeter flange should be smooth and consistent to serve as a perimeter seal surface, thus ensuring long life for the perimeter seal, without being cut, torn or otherwise damaged.
• The desiccant media shall not fracture due to repeated temperature and moisture cycling and all the materials of construction shall be non-toxic.

The surface of the media shall have a special edge hardening so as to ensure a smooth surface and long life of both the media and the seal contacting it. The desiccant media shall not use any organic burn off process, as this shall weaken the media structure.

Process & Reactivation section:

• Special high quality silicon seals, dividing the process and reactivation airstreams, shall be designed to positively seal the two air streams for inter-compartmental air and moisture leakage. The seals shall be made from high temperature silicon rubber with PTFE composition coated face for low friction, durability, and long life. For maximizing the seal life, the perimeter seals should not contact the face of the fluted media, but seal the smooth perimeter flange of the seals will have a long life and will not be cut, torn, or otherwise damaged. Seals should not be fastened, screwed, or riveted, but should be of the slip on type so that the seals are simple and easy to replace with no tools required.
• The reactivation heat source, built into the dehumidifier casing/unit, shall be either steam, electric, or direct fired gas, and installed with filters.
• Both process and reactivation fan and motor assemblies shall be factory mounted as an integral part of the dehumidifier. The process and reactivation fan blowers shall be designed for a minimum external static pressure so as to facilitate the requirement of Process & Reactivation Exhaust respectively.
• The process and reactivation motors shall be of the TEFC (totally enclosed fan rotor, Cooled) type.

Control Panel:

Control panels shall contain factory mounted and wired fan motor starters and auxiliary controls, plus factory mounted and wired terminals strip within the panel conveniently located on the dehumidifier. Both process and reactivation air fans and motors assemblies shall be factory mounted on a tubular structural steel base common with the dehumidifier. Starting and stopping of the unit shall be sequenced by a combined T & Rh sensor.

Auto manual switch to be provided & compatible with B.M.S.

Filters:

All air entering the dehumidifier must be filtered. Unless otherwise indicated, filters shall have minimum rating as per design. Filters shall be installed for front removal, or removal from side of ductwork. All filters shall be of cleanable types wherever applicable.

Volume Control Dampers:

Supply and Return Dampers on Dehumidifier to be of Extruded Aluminium Low Leakage Aerofoil Volume Control Dampers with extended shaft suitable for Manual & Motorised operation.

Pre-Cooling Coil

The process air will be equipped with a pre-cooling coil consisting of the appropriate number of rows, as specified in the Bill of Quantity. This pre-cooling function will be achieved using treated fresh air and a chilled water coil. The coil header shall be constructed with copper for durability and efficiency.
Note: The pre-cooling coil must have a minimum of eight 8 rows or comply with specific design requirements.

Steam Coil

The steam coil system will include mating flanges (ASME B 16.5 150#) for both the steam inlet and condensate outlet to ensure compatibility and ease of installation.

Testing and Commissioning

The units will undergo rigorous testing to validate their capacity, power consumption, and other standard parameters. The dehumidification capacity will be calculated based on measurements of the entering and exiting air conditions, including temperature and relative humidity. Detailed calculations of the dehumidifier’s capacity will be submitted for review

Operating Instructions and Maintenance Manual

The contractor must prepare and submit a draft version of comprehensive operating instructions and a maintenance schedule for the dehumidifiers. Upon approval of the draft, four bound copies of the finalized operating instructions and maintenance manuals, complete with P&ID diagrams, shall be provided.

Common Features of the Dehumidifiers

1. Starter Configuration
   • The dehumidifier starter will be factory-installed and wired.
   • The starter enclosure will have an IP-54 rating, featuring a hinged access door with a lock and key.
2. Overload Protection
   • Microprocessor-controlled motor overload relays will be installed, set at 108% of the rated load amps for each phase.
   • The overloads will include manual reset functionality and will de-energize the main contactor during overcurrent conditions.
   • Adjustable overloads will cater to mid-range settings, with locked rotor trip time set at 8 seconds for full voltage and 60 seconds for reduced voltage.
3. Advanced Motor Protection
   • Incorporates three current transformers and a 3-phase digital ammeter (1% accuracy).
   • Monitors motor current as a percentage of full-load amps for each phase.
   • Provides protection against phase failure/reversal, ground faults, stalls, and high/low voltage.
   • Includes provisions for future relay and contact expansions for integration with a supervisory data center.
4. Additional Features
   • Motors must conform to Efficiency Class 1 standards.
   • Permanent wiring diagrams with a plasticized finish will be affixed inside the panel.
   • Power transducers in each starter will enable remote kW readings via the Building Automation System (BAS).

Controls

• The dehumidifier will feature a stand-alone, microprocessor-based control center for operation and sensor monitoring.
• Integration with the BAS will facilitate:
  • Remote start/stop operations.
  • Humidity and current limit adjustments.
  • Safety and cycling shutdowns.
  • Remote monitoring of operational status.

Installation Guidelines

The dehumidifier will be mounted on a structural steel frame, isolated per the manufacturer’s recommendations to minimize vibration transmission to the building structure.

Performance Testing and Documentation

1. Submittals
   • Drawings outlining components, dimensions, clearances, and connection details.
   • Product data on rated capacities, weights, and accessories.
   • Installation instructions.
2. Testing
   • Verification of all safety features and interlocks.
   • Submission of certified test reports signed by a senior official of the manufacturing company. Pre-printed certifications are not acceptable.
   • Equipment that fails performance standards will undergo revisions and retesting.
3. Noise Compliance
   • Noise levels shall not exceed 55 dB at a distance of 5 meters from the dehumidifier.

Interface with Building Automation System (BAS)

For seamless integration with the BAS, the dehumidifier manufacturer will provide:

• Hardware and software protocols for the microprocessor panel.
• Communication structure for event and message data.
• A comprehensive system overview and permission for the BAS contractor to develop the interface without financial implications.
• Open protocol modules for remote operation, including start/stop and parameter adjustments.

Start-Up and Commissioning

• A factory-trained technician will be provided by the manufacturer for start-up and commissioning at no extra cost.
• The manufacturer will train the owner’s team on the unit’s operation and maintenance, supplying detailed instructions and part lists.
• Testing will be conducted in the presence of the client, with power and water supplied by the contractor.
• Any damage incurred during transit or installation must be repaired, and disassembly/reassembly for access will be performed as needed.

Technical Date to be Provided by the OEM

How to Calculate Dehumidifier Capacity

Key Parameters

• Room Dimensions (Volume): Calculate the room volume in cubic meters (or cubic feet). Volume=Length × Width × Height
• Desired Relative Humidity (RH): Define the target humidity level you want to achieve.
• Current Relative Humidity: Measure the initial humidity level in the space.
• Temperature: Note the average room temperature as it affects moisture load calculations.
• Moisture Load Sources: Identify sources contributing to humidity (e.g., open water tanks, people, equipment, ventilation).

Calculate the Moisture Load

The total moisture load consists of internal and external sources:

External Moisture Load (Ventilation Air):

For outdoor air being introduced into the room:

Moisture Load (kg/hr)=Airflow (m³/hr)×(Humidity Ratio Outside−Humidity Ratio Inside)

• Airflow: The amount of outdoor air entering the room in cubic meters per hour.
• Humidity Ratio: The absolute humidity in kg of water per kg of dry air, derived from psychrometric charts.

Internal Moisture Load:

Estimate based on internal sources:

• People: Each person adds about 0.1–0.2 kg/hr of moisture.
• Processes/Equipment: Consider moisture emitted by equipment or processes.

Determine Dehumidifier Capacity

Add the external and internal moisture loads to get the total moisture load:

Total Moisture Load (kg/hr)=External Load + Internal Load

Convert this to liters per hour: 1 kg of water =1 liter of water

Adjust for Safety Margin

Add a safety margin of 10-20% to account for unforeseen variations in humidity levels or increased moisture loads.

Example Calculation:

• Room Volume: 10 m×8 m×3 m=240 m3
• Ventilation Airflow: 300 m3/hr
• Humidity Ratios:
  • Outside air: 0.015 kg water/kg dry air
  • Inside air (desired): 0.010 kg water/kg

External Load:

300 m3/hr×(0.015−0.010) kg water/kg dry air=1.5 kg/hr

Internal Load (5 people):

5×0.2 kg/hr=1.0 kg/hr

Total Load:1.5 kg/hr +1.0 kg/hr = 2.5 kg/hr1.5

Adding a 20% safety margin:

2.5×1.2=3.0 kg/hr or 3.0 liters/hr

Frequently Asked Questions

What dehumidifier is used in the pharmaceutical industry?

Desiccant dehumidifiers are commonly used in the pharmaceutical industry due to their ability to achieve very low humidity levels, which are crucial for manufacturing, storage, and packaging of moisture-sensitive products.

How do you spec a dehumidifier?

To specify a dehumidifier, consider:

• Desired humidity levels.
• Airflow requirements (CFM).
• Dehumidification capacity (liters or pounds per hour).
• Operating temperature range.
• Integration with existing HVAC systems or Building Automation Systems (BAS).
• Material of construction to resist corrosion.

What are the criteria for dehumidifier selection?

Key criteria include:

• Humidity control precision.
• Room size and volume.
• Moisture load in the environment.
• Temperature conditions.
• Energy efficiency.
• Maintenance requirements.

What are the two types of dehumidifiers?

1. Refrigerant (Condensate) Dehumidifiers: Use cooling coils to condense moisture from the air.
2. Desiccant Dehumidifiers: Use moisture-absorbing materials to remove humidity, suitable for low-temperature environments.

What is the humidity in pharma?

In the pharmaceutical industry, humidity is typically maintained between 35-45% RH, depending on the process and product requirements. For sensitive areas, it may go as low as 1-10% RH.

What is the best material for a dehumidifier?

Stainless steel is the best material for dehumidifiers used in pharmaceutical applications due to its corrosion resistance, durability, and compliance with hygiene standards.

What is moisture content in pharmaceuticals?

Moisture content in pharmaceuticals refers to the percentage of water present in raw materials, intermediates, or finished products, which is critical to ensure stability, potency, and shelf life.

What materials are in a dehumidifier?

Dehumidifiers typically include:

• Coils: Copper or aluminum.
• Casing: Stainless steel or plastic.
• Desiccants: Silica gel or lithium chloride (for desiccant models).
• Fans and Motors: Usually steel or durable plastic.

What is room humidity in pharmacy?

The recommended room humidity in a pharmacy is generally around 40-50% RH, which ensures proper storage of medicines and prevents degradation due to moisture.

What is the basic work of a dehumidifier?

A dehumidifier removes excess moisture from the air, lowering relative humidity levels to create a controlled environment for comfort, safety, or specific industrial requirements.

Why is determination of humidity essential in the pharmaceutical industry?

Determining humidity is vital to:

• Prevent product degradation.
• Ensure the stability and efficacy of medications.
• Avoid contamination and microbial growth.
• Maintain regulatory compliance.

What is a professional dehumidifier?

A professional dehumidifier is a high-capacity, industrial-grade unit designed for continuous operation in demanding environments such as pharmaceutical plants, laboratories, and warehouses.

What is the condition of a dry room?

A dry room typically has relative humidity levels below 1% RH and is temperature-controlled, often used for lithium battery production or moisture-sensitive processes.

What chemical is in a dehumidifier?

Desiccant dehumidifiers may use chemicals like silica gel or lithium chloride as moisture-absorbing agents.

How to reduce humidity in a laboratory?

• Use a dehumidifier (preferably desiccant-based).
• Ensure proper ventilation.
• Seal any openings to minimize external moisture ingress.
• Optimize HVAC systems to maintain desired conditions.

What is humidity in a pharma company?

Humidity levels in pharmaceutical companies vary depending on the process, but manufacturing and storage areas typically maintain 35-45% RH or lower for critical processes.

What is important when buying a dehumidifier?

Consider:

• Humidity control range.
• Capacity and coverage area.
• Type (refrigerant or desiccant).
• Energy efficiency.
• Noise level.
• Build quality and compliance with industry standards.

Where are industrial dehumidifiers used?

Industrial dehumidifiers are used in:

• Pharmaceutical manufacturing and storage.
• Food processing plants.
• Electronics manufacturing.
• Cold storage facilities.
• Archives and libraries.

What is the humidity in a dry room?

The humidity in a dry room is typically less than 1% RH, ensuring an ultra-low moisture environment for specialized industrial applications.

Humidity Control In The Pharmaceutical Industry