Constant Temperature and Humidity System for the museum showcase

Constant Temperature and Humidity System for the museum showcase include PMCG & MINI ONE Active Humidity Generator and Maxi One microclimate generator.

PMCG Microclimate Generator
PMCG Active Microclimate Generator without adding draining water

PMCG - Active Microclimate Generator for Museum Showcases

The PMCG humidity generator is a novel approach for controlling humidity in museum quality display cases. The PMCG units are based on solid state technology - unlike other units, they don't require filling or emptying of reservoirs.

Once the machine is setup, the humidity inside the display case is maintained for years without the necessity of checking the water level, adding water or any other regular maintenance. PMCG devices are able to maintain relative humidity from below 25% up to 60% at ambient temperatures of from below 0°C up to 40°C. PMCG units are of modular design; the main unit can be connected to many slave units to achieve the necessary capacity for a particular application. Thanks to this design the client pays only for the needed capacity. The units are very quiet (<16 dB), use very little power, and needs no special ventilation

Museum Showcases Active Microclimate Generator

MINI ONE - Active Humidity Generator for Museum Showcases

The Mini One humidity generator is a miniature, positive pressure humidity control device for museum showcases and storage enclosures. This quiet, robust and extremely efficient unit can reliably control relative humidity in individual or multiple enclosures.

The Mini One satisfies the demanding standards of preventive conservation and modern museum design. It incorporates the most recent developments in electronic humidity control, noise suppression, and pollution abatement – and is built on the heritage of a series of microclimate control devices extending back to 1978.

This positive pressure microclimate control system will typically maintain the relative humidity level in a sealed enclosure to within less than two percent of your target relative humidity. Depending upon the ambient temperature conditions and enclosure construction, stable relative humidity levels of less than thirty to over eighty percent can be attained.

MINI ONE Active Humidity Generator Model

As the Mini One can be installed in a number of configurations for differing applications, performance characteristics will vary with installations and enclosures. In its most common application, the unit will provide a constant flow of filtered air at a pre-set relative humidity level.

This air is directed through a small flexible tube to an input port in the showcase.Air flow to the enclosure is constant, and in normal applications the air is delivered only at the preset relative humidity.

In normal configurations, the unit provides humidity control for a single tightly sealed enclosure, usually not exceeding 10cubic meters. In these applications the unit will typically provide extremely accurate humidity control; the unit neither adds nor subtracts moisture from the air in the showcase – it gently feeds a steady stream of air into the showcase at the target humidity to displace the existing air and pollutants in the enclosure, which is forced out past gaskets and through small existing leaks.


Max. Power Consumption: 95W
Typical Power consumption: 65W
Power supply: 110 - 240VAC
System Internal Voltage: 12VDC
Case Material: powder-coated aluminum
Shipping weight: 15kg
Output: 35%-80%
Output Volume: 24m/day
Max output volume: 40m/day (contact manufacturer for info)
Output pressure: ~2" H O (600 Pa)
Operating Temperatures: 15 to 27 degrees C (60 to 80 degrees F) (Ambient temperatures will affect control capacities)
Sensor Element: Capacitive thin-film sensor
Sensor Reading Accuracy: +/-2% over mid-range
Sensor Repetitive Accuracy: +/-1%
Biocides: Copper components, chilled compartments, and TiO2 mesh
Standard accessories: air pump, air pump hose, funnel, exhaust hose, exhaust termination, air supply hose, through wall connector, sensor, power cable.
Optional accessories: largediameter silicone air hose, "T" connectors.

Maxi One Constant volume humidity generator
Preservatech Maxi One
Museum Showcase & Storage Enclosures Microclimate Remote Control Unit

Maxi One - Constant volume humidity generator for Museum Showcases.

Preservatech's Maxi One microclimate generator is a fully automatic positive pressure air supply device, designed to provide conservation-quality humidity control for museum display or storage enclosures. A single unit in a remote location (such as a machine room) can reliably maintain extremely stable humidity control and pollution abatement for an entire gallery of showcases.

Suggested Applications:

Use these units to supply air to multiple display cases, the very large volume showcases, multiple storage enclosures or small archive rooms where:
Energy cost savings of up to 50% are to be realized.
Accurate humidity control in new or renovated galleries may be expensive or impractical.
Existing air conditioning systems or building envelopes cannot maintain adequate humidity control.
Existing display cases with moderate to high leakage rates must be used, or cost savings must be found on new display or storage cases.
Pollutants or dust from internal or external sources must be purged from cases.

General Operating Principles

These units provide a continuous low-pressure flow of filtered air to display or storage cases, gently displacing case air and pollutants. Air is supplied as a positive pressure feed only, there is no return flow. Displaced air from the case is exhausted through naturally occurring leakage.

Display cases are fed by an air delivery system consisting of distribution pipes and small hoses. Air enters the display case through a small unobtrusive hole, requiring minimal modifications. MAXI ONE units operate independently of building HVAC systems.

The ultimate control capacity of any MAXI ONE unit will be dependent on a number of factors, including target humidity, enclosure size, enclosure leakage, air distribution system, average ambient temperatures and the degree and speed of ambient temperature changes. Each MAXI ONE unit can supply a large number of cases of varying sizes. We can recommend a consultant to assist you in determining the most effective device for your application.

Typically, a single unit can supply a constant flow output air at an RH level from below 35% to above 60% at ambient temperatures of 70 degrees F / 21 degrees C. Lower ambient temperatures will allow the unit to maintain lower delivery RH levels Output variation at constant temperature is typically less than +/- 1%. Depending on unit and application, outputs can be from less than 15 to over 60 cfm / 500 to 2000 lpm, with a maximum treatment capacity of from 5,000 to 25,000 cubic feet / 150 to 900 cubic meters of display or storage enclosure(s).

The moisture content of the supplied air will be automatically adjusted with changes in ambient temperature to provide constant RH. (Output change is limited to a change in a dew point of not more than 2.5 degree C per hour.) The unit will respond to changes in ambient temperature by modifying its humidity output, but will not influence or control display case temperatures. No operator adjustments to fan speed, pressure, or delivery rate are needed (or possible).

The output from the unit is constantly monitored by a sensor mounted in the gallery. Airflow outside of preset limits will be dumped by an electromechanical valve. Air is filtered for gaseous and particulate pollutants upon intake to the MAXI ONE unit, and output air is filtered through a HEPA grade filter.

Unit Location, Air Distribution Layout, and Installation

The MAXI ONE unit can be located up to 400 feet / 150 meters from the gallery. The unit may be placed in a machine room, janitorial closet, or any space with adequate room for the unit, ventilation, water supply, floor drain, and power connections. The footprint of the unit is 3 ft wide X 2 feet deep (90 cm*60 cm), and space should be allowed to access the unit for control and maintenance. Unit should be floor mounted and comes on casters for easy movement.

The unit comes complete with a high quality temperature and humidity sensor. One sensor for each MAXI ONE unit must be located in the gallery. Sensors may be wall mounted, or placed in a "representative" showcase. Microclimate data is returned to the control panel on the unit by cable or wireless system.

The air distribution system is an integral and major component of this microclimate control system. Appropriate pipe locations, sizes, supply nodes, and placement of the safety dump valve and sensor should all be planned as early a possible in the design process. As the operating paradigms and air distribution system of MAXI ONE units are quite unique, common paradigms for installation and air ducting are usually not applicable.

The most common style of installation is "tree and branch" air supply systems usingtwo inch lightweight copper (DWV) pipe running from the machine to the gallery, with delivery to the cases via one half inch rigid pipe or flexible hose. Bends in the system should be minimized. Other pipe sizes, materials (ABS plastic, etc.) and designs (eg "spoke and wheel" or multiple node style) or other distribution systems may be recommended, depending on installation.

We strongly suggest you engage an appropriate consultant to assist your relevantarchitects, engineers, and museum designers with preliminary planning of unit and air distribution systems to ensure a successful installation. Preparation of the machine location and installation of air distribution system can be done by standard trades. Our guarantee is limited to the operation and delivery capacity of the unit, not it's interface with the enclosures nor their behaviour.

All units are supplied complete with locking casters, plugs and sockets for electrical and wiring connects, and standard compression plumbing fittings, so that units may be easily rolled into position and quickly installed.

Typical Air Distribution Diagram

This diagram represents the most common air distribution designs. Many variationsare possible.

Maxi One Typical Air Distribution Diagram

For piping sizes and specifications, see Contractor's Data SheetAir enters cases via Bulkhead fittings (1/2 inch ID) or other small holes.
1. The flexible hose connecting MAXI ONE to Delivery Pipe (minimum 2' / 60cm)
2. Delivery Pipe from MAXI ONE unit in machine room to Dump Valve (up to 400 ft / 125m away)
3. Drop Line to Sensor Box
4. Dump Valve
5. Trunk Pipe from Dump Valve to wall, floor, or ceilings proximate to Showcases
6. Multiple Drop Lines from Trunk Pipe to Showcase (eg. rigid pipe / flexible hose /valve / flexible hose)

Note that bends are 45 degrees rather than 90 degrees

Technical Specifications:
Unit Size: 36" wide x 24" deep x <72" height (including 4" diameter swivel casters) Nominal Weight: <300 lb (reservoir empty), <500 lb (reservoir full)
Power Supply: As Requested, or 110V/220V/1/60, 3 wires plus ground, 30 Amp
Nominal Power Consumption: 12 Amps @ 220V when generating 50% RH @ 21CMaximum Operating Amperage: 23 Amps @ 220V/1/60
Operating Temperatures 10 - 30 degrees C; Gallery temperatures have no effect on unit mechanical operation, but will affect achievable humidity levels
Filter Media: Intake filter: Combination of (Carbon / PP / Fine Particulate filters); Exit filter: HEPA grade, or As Requested
Water Supply: 1/4" hose connection for domestic line, or optional reservoir
Drainage: Floor drain in vicinity of unit, or optional containment tray
Output: When shipped, the MAXI ONE may be optimized to provide a constant flow of RH tempered air at tolerances as low as +/-2% within an operating range of 15 to 30 degrees centigrade at a flow of up to 60 SCFM / 2000 lpm and pressures of 3 to six inches wc at the output pipe. This air flow may be adequate to supply up to 600 cubic meters of display cases at four air changes per day. Ultimate device capacity will depend on the combined leakage of cases, layout of supply runs, and desired performance parameters.
Standard Accessories Included: Off-site alarm connections; gallery mounted sensor box; electromechanical dump valve; operating manual and trouble-shooting guide


Provides conservation quality humidity control for very large display volumes, or multiple storage cases.
Accurately and consistently delivers humidity levels within 2% of set points.
Higher pressure output allows for effective and inexpensive air distribution systems.
Positive pressure ventilation with filtered and scrubbed air reduces case maintenance; pollutant and particulate inflow into cases is prevented.
Off-gassed pollutants generated in the cases are constantly flushed; the constant airflow also prevents stratification.
High volume airflow allows for reuse of antique, or less efficiently sealed cases.
Remote central unit provides silent, invisible protection from up to 500 ft / 160 meters away via an unobtrusive system of pipes and tubes.
Designed and manufactured with the best quality industrial components for extreme reliability.
Multiple level failsafe systems and self monitoring diagnostics.
User friendly controls, including accurate and comprehensive electronic readouts.
Multi-point Building Management Service connections, and complete data logging options.
Maintenance is minimal.
Installation is simple and unobtrusive- use with existing or new galleries.
Individual cases may be easily added to, or removed from, the system.
Portable- unit moves on casters, new mechanical connections are easily supplied; unit may be easily used for alternate applications as needed.