7.0) Water (drying): (page 5 of 5)

7.32) HVAC Systems: HVAC systems have passageways that distribute clean air; be it fresh, makeup, cooled or heated, to spaces that are generally occupied by persons, pets, belongs, etc., while bacteria, mold (fungi) and contaminates foil the passageways intention.

The remediation of HVAC systems after a water loss should conform with Sections 3.23.c, 3.23.d, 6.37, 6.37.a and 6.37.b, and the cleaning and remediation standards and guidelines developed by the National Air Duct Cleaning Association (NADCA).

7.33) Building Insulation: The remedial actions best suited for insulation after a water loss would depend on the insulations style, characteristics, if there is mold formation and the severity of the damages caused by the water or moisture.

Mold (fungi) formation on synthetic insulation is generally due to organic soiling as affixed to the insulation during construction, such as wood dust.

When water or secondary damage has jeopardized the insulations R-value or fire rating, it should be replaced.

Blanket and batt insulation constructed from fiberglass has an absorption rate of 0.05% or less and could be dried when moderately affected by water or moisture. 

Additional remedial information on building insulation can be found in Section 6.21.n.

7.34) Drying Equipment: The loss type (category/situation), surface types, and post-condition (what is wet? and how wet is it?) would determine  the type and quantity of equipment needed to mitigate and neutralize a water loss site.

When determining the quantity of equipment needed, the number of rooms affected, the cubic feet of affected rooms, temperature, humidity, rate of wicking, and moisture content of building components and content items should be used as a basis.  When sizing dehumidification equipment, the water site drying classifications in Section 7.42 should be used as a starting point.

Equipment left on site in an operable state for a considerable amount of time should be inspected at least once in a 24-hour period, and this should include, but not be limited to; airmovers, dehumidifiers, generators, etc., and as conditions improve, pieces of equipment should be removed.

7.35) Pumps: Pumps are used to move water from one area to another, and there are several types of pumps available to achieve this goal:

   - Low & high-pressure pumps
   - Utility pumps
   - Trash pumps

Utility pumps, a/k/a trench/ditch pumps are used to remove standing water at several inches deep and some are submersible, while pressure and trash pumps can remove water several feet deep. 

Low & high pressure pumps can be self-priming, or need priming assistance. 

Trash pumps are designed to move waters containing, mud, dirt, stones, sticks, etc.

When pumping basements or lower levels after flooding, the ground pressure outside the structure should be less than the pressure inside the structure to prevent wall cracking or collapse of the structure.

Recommended pumping procedures for basements is available at MisterFixIt.com/Flood.htm.

Pumps are rated at gallons per hour (GPH) and lift, and the U.S. gallons into cubic feet table would be helpful when sizing pumps and calculating time frames.

Each pump has its application, and pumps should only be used for the applications they are designed for. 

7.36) Extraction Equipment: Extraction machines would be portable or truck mount, and each has its benefits and limits.

Truck mount units offer large volume extraction, but are limited on multi-level properties, while portable units are emptied more often, yet are versatile in multi-level properties.

Extraction equipment should be in excellent working order and spare parts, such as jets, couplings, valves, etc. should be on hand.

 

7.37) Airmovers: There are several types of airmovers designed specifically for structural drying:

    - Turbofans
    - Vortex Air Mover
    - High Velocity Fans
    - Low AMP Air Mover

Turbofans are designed at a low center of gravity to force air along floor and wall surfaces, while axial fans are designed to force a large volume of air across a large area.

Typically, one (1) airmover per 300 SF minimum when drying, or three (3) airmovers per one (1) dehumidifier --- depending on the dehumidifiers rate of evaporation. (ref. 7.38)

Professional brand airmovers have varying accessories available to aid with the drying process:

    - Turbovents
    - Turboduct
    - Mini-Turbovents
    - Flexible Ducting

When performing water loss mitigation, residential box fans, circular fans, etc. should not be used due to possible electrical shock or electrocution.

7.38) Dehumidifiers: Dehumidifiers are available in refrigerant or desiccant, and the sizing of a refrigerant dehumidifier is based on grains (gpp) of moisture it can draw from the air in a 24-hour period, and a desiccant dehumidifier is sized by the CFM, as illustrated in Table 7-G and Table 7-I.

Refrigerant (coil) dehumidifiers condense moisture from the atmosphere onto chilled coils, while desiccant dehumidifiers absorb the moisture from the air.

Standard refrigerant dehumidifiers can operate at temperatures as low as 67º F.  Commercial dehumidifiers with hot gas bypass operate as low as 40º F.  Heat pump dehumidifiers operate down to 33º F.  And desiccant dehumidifiers operate down to 32º F or lower.

The sizing of dehumidifiers (refrigerant and desiccant) is listed within Table 7-I, at the bottom of this page.

7.39) Chemical Dispensers: There are several applicators available to dispense chemicals and cleaning agents:

    - Ultra low volume (ULV) foggers
    - Electric sprayers (airless)
    - Hydo-Force injection sprayers
    - Hand pump sprayers
    - Trigger sprayers

Each dispenser is designed for a specific application such as; room volume, surface area and within hidden cavities, and dispensers should only be used for the applications they are designed for.

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7.40) Injection Drying: Injection drying equipment as manufactured by Injectidry Systems and Dri-Eaz Products are pressure drying equipment that offer both positive and negative pressure.

Injection drying equipment when used in the right application and set up properly will reduce the size of access hole penetrations in walls, cabinetry, and flooring materials as well as reduce drying time and prevent secondary damages. 

7.41) Meters and Instruments: Contractors will use several types of meters and instruments during mitigation:

    - HydoSensor moisture probe 
    - Thermo-Hygrometer 
    - Moisture meter (penetrating and non-penetrating)
    - Psychrometric calculator
    - Dehumidifier calculator 
    - Thermal Imaging

The hydrosensor, penetrating meter and non-penetrating meter operate as continuity meters and provides reading when a DC volt circuit is completed.  Thermal imaging camera uses infrared technology, providing a heat differential.

7.42) Loss Site (Drying) Classification: During the evaluation of a water loss site, technicians should determine the drying classification as set forth by the IICRC.  The classifying of a water loss site by its evaporation rate, as affected by the permeance of the structures building components and content items, should provide technicians a starting point on dehumidification needed. Table 7-A provides a brief listing of building material permeance.

The four IICRC water damage classifications are as follows:

Class 1: Slow Evaporation Rate: Water losses that affect only part of a room or area, or losses with lower permeance/porosity materials (e.g., plywood, particle board, structural wood, VCT, concrete).  Little or no wet carpet or cushion is present. Minimum moisture is absorbed by materials, releasing moisture slowly.

Class 2: Fast Evaporation Rate: Water losses that affect an entire room or carpet and cushion. Water has wicked up walls 12" - 24”.  There is moisture remaining in structural materials (e.g., plywood, particleboard, structural wood, concrete).

Class 3: Fastest Evaporation Rate: Water may have come from overhead. Ceilings, walls, insulation, carpet, cushion and sub-floor in the entire area are saturated.

Class 4: Specialty Drying Situations: These consist of wet materials with very low permeance/porosity (hardwood, plaster, brick, concrete, stone, crawlspace).  Typically, there are deep pockets of saturation, which requires very low specific humidity.

Technicians should evaluate the water loss site to determine their psychrometrics, materials permeance, etc., and base their dehumidification on the cubic foot of air within the affected areas based on the following steps:

Step 1: Calculate the affected areas into cubic feet.

Step 2: Determine water loss Class (#1, #2, #3, or #4).

Step 3: Calculate total number of pints dehumidification equipment will remove based on Association of Home Appliance Manufacturers (AHAM) test conditions at 80° F / 60% Rh.

Step 4: Based on AHAM performance per 24 hours, the total dehumidification needed should be calculated by dividing the factor into the total cubic feet of the area being dried as shown in Table 7-I.

The Classifying of water damages as explained in this section should only be a starting point based on the loss site evaluation and conditions.  Adjustments should be made as determined by daily drying records and loss site conditions as they change.

7.43) Heat (convection) Drying Systems: As described in Section 7.11.a, temperature could be considered the balance point of a drying system, since moisture, water and the materials that make up the built environment all react to heat.

When using heat to mitigate (dry) a structure, the interior atmospheric temperature should be maintained between 95° F to 105° F.  While interior atmospheric temperatures maintained at 105° F to 110° F, when properly set-up and monitored should reduce drying time. (ref. Section 7.43.c)

Convection (heat) drying systems can reduce structural drying time by 10% to 30% at minimum, depending on what is wet?, the materials saturation and the experience the drying technician has with the drying system, as well as with the built environment that is being dried.

For a heat drying system to be efficient and prevent secondary damages, air movement and air exchanges should be part of the heat systems equation:

Forced Convection = Heat + Air Movement + Air Exchanges

The heat drying process should operate as a convection system, where the moisture is transported to the exterior of a structure through air changes.

When drying with heat, 3 to 4 air exchanges per hour is recommended.  Moreover, uniform heat throughout a wet structure is recommended during the drying process, and supplemental low grain dehumidifiers should be used to gain uniformity, when required.

7.43.a) Net-Positive Pressure: Since moist air will travel to dry air, when it can.  Heat drying systems should maintain a net-positive pressure during the drying process when the specific humidity produced by the drying system is lower than the relative humidity at the exterior of a structure, which would produce excess infiltration if the drying system is not properly balanced. (ref. 7.15.a)

7.43.b) Heat Precautions: Temperatures in excess of 95° F, when used to dry a structure, would require a pre-evaluation of the property being heated to determine what may or may not be affected by heat.

Items such as painting, pictures, books, candles, musical instruments, antiques, etc. should be classified at low heat sensitive and should be protected or removed during the heat drying process.

When ducting heat, flexible ducting should be insulated to prevent damage to grass, shrubbery, window sashes, doorways, etc.

Fire suppression systems (i.e., fire sprinkler, halon, fire alarms & smoke detectors, etc.) could require protective means or be disarmed before the heat drying process begins.

Before a fire suppression system is altered, protected or disarmed, the local fire authority, manufacturer of the fire suppression system and all occupants of the building should be notified.

When using heat drying systems, the manufacturers use practices, safety precautions, and heat sensitive materials listing should be followed.

Heat drying system manufacturers and technicians are encouraged to develop a universal materials heat sensitivity chart for the mitigation, remediation and restoration industries.
 

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7.43.c) Drying System: The following firms offer heat drying systems:

- Aquadry Systems, LLC
- Ground Heaters, Inc.
- TES Drying System
- ThermaPureHeat
- Water Out

7.43.d) Other Heat Applications: Due to the characteristics of heat --- heat systems can also be used as:

- Supplemental system to kill mold spores, in lieu of disinfectants^{(1) (2)}
- Pasteurization for treating bacteria, in lieu of disinfectants ⁽²⁾
- Document drying system, when documentation is wet/flooded due
  to sewage back-flow ⁽²⁾
- Extermination, in lieu of pesticides ⁽²⁾
- Odor removal ⁽³⁾

(1) Does not supplement the physical removal of mold spores.
(2) An industrial hygienist should always be consulted when using heat for mold, bacteria, sewage or extermination.
(3) Does not supplement the physical removal of the odor source.

When using heat for disinfecting, the contaminate  being treated would determine the heat reaction time required.

For additional information on using heat for other processes, see Section 8.0. (coming soon)

 

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Extracted from the Loss Recovery Guide with Standards (LRGS)
© Copyright 1998-2008 William Yobe

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