A sanitary tank bottom valve with constant pressure regulation holds outlet pressure steady as tank level falls. A spring-loaded diaphragm adjusts flow area to offset the changing head. Fill weight stays repeatable from the first container to the last. The body uses SS304 or SS316L with a welded connection and a 0-8 bar range.

How Falling Head Affects Fill Weight

As a tank drains, the liquid level drops and static head falls. Outlet pressure decreases through the filling run. Early containers receive more product than later ones. Fill weight drifts outside tolerance.

Falling head reduces outlet pressure.
Fill weight drifts through the run.
Early containers overfill.
Late containers underfill.

Overfilling wastes product and can breach container limits. Underfilling shortens the declared net weight and breaks labeling rules. A drift of a few grams per container adds up across a production shift.

Diaphragm Regulation and Spring Setting

A spring presses against a diaphragm that senses outlet pressure. When pressure falls, the spring opens the diaphragm and admits more flow. When pressure rises, the diaphragm restricts flow.

A tank bottom diaphragm valve uses a similar diaphragm, but it acts as a shutoff rather than a regulator. Some skids combine both functions in one body.

Parameter	Value
Body material	SS304 / SS316L
Connection	Welding
Pressure	0-8 bar
Diaphragm	EPDM / PTFE
Surface finish	Ra ≤ 0.8 μm
Operation	Spring loaded

Spring selection sets the pressure the valve holds. A spring rated below the filler inlet pressure starves the heads. A spring rated above the filler limit forces product past the seals. Match the spring to the filler requirement before startup.

Body Layout and Drainability

The body drains through the low port when the line shuts down. A sloped outlet lets product leave without pooling at the diaphragm. A tank bottom valve placed at the vessel outlet uses gravity to drain the line. The same body shape suits both shutoff and regulating duty.

Selection Criteria for Constant Pressure Valves

Several factors decide the correct valve size and spring setting:

Tank height and maximum static head.
Filler inlet pressure requirement.
Product viscosity and flow rate.
Line size at the tank outlet.
Cleaning cycle temperature and chemical exposure.

A valve sized too large cannot regulate low flow rates. A valve sized too small restricts the filling speed. Check the flow curve against the filler demand before ordering.

Material and Surface Finish

Wetted parts use SS304 or SS316L for corrosion resistance against acidic products and repeated SIP cycles. Internal surfaces reach Ra ≤ 0.8 μm. Electropolishing lowers roughness toward Ra ≤ 0.4 μm and reduces attachment sites for microbes. Smooth faces release soil during cleaning.

Installation and Setup

Confirm the weld end matches the tank outlet size.
Mount the valve so the body drains by gravity.
Set the spring to the target outlet pressure.
Run a fill cycle and check volume across the batch.
Inspect the diaphragm and seat at scheduled intervals.

Common Applications

Constant pressure valves serve lines that need steady outlet pressure. The tank outlet mount suits filling and bottling duty.

Beverage bottling and canning lines
Dairy filling and pouch packing
Pharmaceutical solution dosing
Food sauce and syrup filling
CIP supply pressure control

Set Pressure and Batch Verification

The spring sets the outlet pressure the valve holds. A setting below the filler requirement starves the heads and slows the line. A setting above the filler rating forces product past the seals.

Check the spring against the filler inlet pressure before startup. Run a volume check at the start, middle, and end of each batch. Log the set pressure and fill weights so drift shows up before containers fall out of tolerance.

Troubleshooting Fill Weight Drift

If weight drops steadily through the batch, check the spring for fatigue and the diaphragm for slow leakage.
If weight fluctuates, look for air in the line or a valve sized too large for the flow.
A worn seat ring also causes drift because it changes the open area at a given pressure.
Replace the spring and diaphragm as a set when drift exceeds the fill tolerance.
Check the tank vent for blockage that would slow the drain rate.
Verify the filler nozzle for wear that changes the back pressure.

Sanitary Stainless Steel Constant Pressure Valve

Constant pressure regulating valve which in its outlet and inlet to ensure a stable pressure, so widely used in separators, heat exchangers, the back of canned systems and other equipments, as well as the relief valve.
Constant pressure regulating valve series are remotely operated by compressed air, the series of valve operation does not depend on the pipeline transportatjion of products of any sensor, requiring only a compressed air pressure regulator for the devices and a pressure guage on the product pipelines monitor the pressure. A diaphragm/stem system san transport the product of the rapid reponse to any pressure changer and change stem position so theat continue to mantain pre-set pressure valve. When the delivery pressure of the product increases, the valve opens, on thecontrary, the valve closed.