Test Method: D1748
Rust Protection by Metal Preservatives in the Humidity Cabinet
• Conforms to ASTM D1748 and FTM 791-5329
• Automated Water Level Control
• Automated Hood Opening with Timer
• Capacity for 33 Test Panels
• Temperature Stability of ±0.5 °C

Model 423 Humidity Cabinet conforms to the design and specifications of ASTM D1748 and FTM 791-5329 test methods for measuring rust protection of metal preservatives. The rack rotating at 0.33 ± 0.03 rpm has a capacity for 33 test panels. The cabinet’s humidity environment is maintained at 48.9°C ±1°C by a digital indicating controller. Air flow to the 20 spargers below the water level is metered at 31 ± 1 cu ft/hr by a float in glass tube flowmeter (mass flow controller is available as an option).

A secondary controller of the water temperature acts as a safety over temperature limit in the event of primary controller failure.

The bath and internal construction is all stainless steel. The outside cabinet construction is of anodized aluminum frame and painted aluminum panels. The cabinet is mounted on lockable casters for ease of positioning in the lab. The distilled water level within the bath is automatically maintained at 8 inches. The bath has a 94 liter capacity. A pan collects the drippings from the test panels and is drained to the outside.

The light weight, hinged cover has two layers of airplane cloth (as specified by ASTM D1748). As an option for Model 423 humidity cabinet, a timer and mechanism is provided that automatically opens and closes the cover to the specified angle of opening and for the required exactly 15 minutes and 5 minutes every day at the same time of day (except Saturdays and Sundays). An alarm alerts the operator as the cover is opening. This feature assures that the test method is followed more carefully, relieving the operator from this repetitive task.

Model DB-1 is the panel draining box as is specified in Fig A1.4 of ASTM D1748 test method. It is constructed of anodized aluminum and plywood as indicated in the test method.

Available Models
Model No.
Number of Test Positions

Part No.
Allendum Air Diffusers
Airplane Cloth
Aluminum Oxide Cloth (240 grit - 50pcs)
Blank Specimens
Polymethyl methacrylate dummy panels, each
Stainless steel dummy panels, each
Additional Hooks (50pcs)
Spare Heater
Test Specimen Drain Box, plywood (per Annex A1 Fig. A1.8)

Specifications are subject to change without notice.

Specifications subject to change without notice. Lawler Manufacturing Corporation © 2011