The Armstrong ASDV is an ambient sensing drain valve ideal for the protection of piping, valves, fittings, pumps, condensate systems, safety showers, fire lines, spray nozzles, and freeze-sensitive equipment. It can also be used as back-up protection on steam-traced systems or equipment. The ASDV provides reliable freeze protection for condensate systems operating up to 300 psig (20.7 bar).

Operation

The ASDV thermal element senses ambient temperature, and at a pre-set temperature, the drain valve will open. Water from the line will then flow past the element. If the water temperature becomes high enough, the valve will then close. If the water temperature is low, the valve will modulate to maintain temperature or will open to drain completely. The valve will be fully open at 35°F (2°C). On rising temperature, the valve will be tightly closed at 40°F (4.4°C).

Advantages

Manual freeze protection with cracked valves for continuous drainage is wasteful and possibly susceptible to freezing. The ASDV automates freeze prevention and reduces waste by opening only when freezing is imminent and closing when the danger is past. Water loss is minimized, and damage and downtime are eliminated. The unique ram-type plug and seat provide reliable, tight shut-off longer than any other design. All valves are 100% factory tested.

Design Features

• All stainless steel body, fittings, spring, and plug
• Corrosion resistant for long life
• Narrow temperature band
• Compact low mass; fast response
• Ram-type plug for reliable tight shut-off
• Downstream actuator for greater sensitivity
• Sensitive to temperature only
• Unaffected by pressure variations
• Easy installation with simple wrenches

Specifications

Specification	Value
Maximum Operating Pressure	300 psi, 20.7 bar
Maximum Operating Temperature	Saturated Steam Temperature
Full Open Temperature	35°F (2°C)
Full Closed Temperature	40°F (4.4°C)*
Flow Coefficient Cv (3/8" and 1/2")	Port Sizes: A - 0.13, B - 0.57, C - 0.82 (Std)
Flow Coefficient Cv (3/4")	Port Size: D - 2.0 (Std)

*Other set-points available with longer lead times and minimum quantities required.

Materials

Item	Name of Part	Material
1	Tubular body	304 Stainless Steel
2	Inlet fitting	303 Stainless Steel
3	Seat seal	PTFE
4	Operating spring	Stainless Steel
5	Ram-type plug	303 Stainless Steel
6	Thermal actuator	F.M. Brass **
7	Actuator carrier	F.M. Brass **
8	Outlet fitting	303 Stainless Steel

** All Stainless Steel models available.

Dimensions and Weights

Size Tube OD (in)	D in (mm)	L in (mm)	Weight lb (kg)
3/8 or 1/2	1-1/8 (28)	4-1/2 (114)	3/4 (0.31)
3/4	1-3/8 (34)	5-1/2 (160)	1-1/4 (0.54)

Flow Capacities and Cv Calculation

Approximate Cv Required Uninsulated* For Freeze Protection of Water Lines

1. Calculate GPM:GPM = [A₁ × A₂ × (0.5 × t_w - t_a + 16)] / [40.1 × d² × (t_w - 32)]

Where:

• GPM = gallons per minute of water flow
• A₁ = pipe flow area, ft²
• A₂ = exposed pipe surface area, ft²
• t_w = temperature of resupply water, °F
• t_a = minimum air temperature, °F
• d = ID of pipe, ft

2. Calculate Cv:Cv = GPM / √(ΔP)

Where:

• Cv = total required Cv of valves
• ΔP = pressure drop across valves (if valves discharge to atmosphere, ΔP = P_s where P_s is supply pressure.)

EXAMPLE CALCULATION

Freeze protect a 125 foot long run of 2" pipe when the minimum air temperature is -15°F. The resupply water is 40°F minimum, at 60 psig.

From pipe data chart, for 2" schedule 40 pipe:

• A₁ = 3.36 sq.in. = 0.023 ft²
• A₂ = 0.622 ft²/ft × 125 ft = 77.8 ft²
• d = 2.067 in. = 0.172 ft

1. GPM = (0.023 × 77.8 × [(0.5 × 40) - (-15) + 16]) / (40.1 × 0.172² × (40 - 32))GPM = 9.6
2. Cv = 9.6 / √(60) = 1.24

Choose the valve or valves required to give a Cv of 1.24 or more; in this case a single C port ASDV. In some cases, a single valve will suffice; however, the use of several smaller valves will improve reliability.

TIP

*For properly insulated lines, use 25% of the Cv indicated as an approximation of required Cv.

Manifold Assembly