CA14 SG Iron Air and Gas Trap

CA14 SG iron air and gas trap for continuous liquid drainage

The Spirax Sarco CA14 is a float-type automatic liquid drainer for air and gas systems. It is intended to remove condensate or other drained liquid while retaining the pressurised gas in the system. The product uses an SG iron body and cover, a float-operated internal mechanism and a Viton main valve cone. It is a continuous-discharge design: liquid entering the chamber raises the float and opens the main valve, while air or gas lowers the float and allows the valve to close tightly on its seat. This operating sequence is useful where a low point, receiver, separator, aftercooler or similar item must be kept clear of accumulated liquid without relying on manual draining.

CA14 is an air and gas trap, not a steam trap. Its documented duty is air or gases within PED Group 2. It is not suitable for PED Group 1 liquids or gases. That distinction is important when a system uses compressed air, an industrial gas or a changing liquid load: the model should be selected from the actual fluid group, pressure, temperature and drainage arrangement rather than from a generic trap label. The technical information and the installation guide below preserve the formal product limits and the safety conditions that must be checked before installation.

Why a float-operated liquid drainer is used

The principal engineering advantage of a float mechanism is its response to the liquid level in the body. There is no need to wait for a thermostatic element to react or for a timed device to cycle before the discharge valve can open. As liquid collects, the float rises and the lever mechanism opens the valve. When gas reaches the trap, the float falls and the main valve closes. This lets the CA14 discharge as the drainage load changes and helps avoid continuous loss of the system gas through the drain point.

That simple description does not remove the need to consider the whole drainage circuit. A float trap must be able to fill, discharge and equalise correctly at the installed pressure conditions. The CA14 is documented as safe under full vacuum conditions, but the available differential pressure, liquid specific gravity, downstream pressure and the way the drain is piped still determine whether the selected arrangement can deliver the required result. These are operating relationships, not independent catalogue figures. The differential-pressure table in the technical section should therefore be read with the liquid being drained and the real line conditions in mind.

CA14 construction and connection options

The standard CA14 has an SG iron body and cover with a Viton synthetic-rubber valve cone. The complete unit is designed to be readily maintainable. The published construction uses stainless steel for the main seat, float and lever, pivot frame and pivot pin, while the cover gasket is reinforced exfoliated graphite. This material arrangement supports a compact mechanical drain trap while keeping the seating, float and pivot elements suitable for their operating functions. The technical information records the complete material schedule and the service-item references; those details should be used when specifying replacement parts.

For screwed pipework, CA14 is available in 1/2 in and 3/4 in sizes with BSP T Rp (ISO 7-1) or NPT connections. The installation guide also documents CA14 flanged versions in DN15, DN20 and DN25 with EN 1092 PN16, ANSI 150 or JIS/KS 10 flanges. For the flanged versions, the cover provides a 1/2 in tapping for a balance line, and the product can be specified for right-to-left or left-to-right horizontal flow. Connection selection is therefore more than nominal size: it should state the required screwed or flanged form, the applicable connection standard and, for a flanged model, the required flow direction.

Pressure, temperature and liquid-density relationship

The CA14 body design condition is PN16. The selected technical information states a maximum allowable pressure of 16 bar g at 120 °C, a maximum allowable temperature of 250 °C, and a maximum operating pressure of 16 bar g. For CA14, the maximum operating temperature is 200 °C at 14.7 bar g. The minimum allowable and operating temperature is 0 °C, and the product has been designed for a maximum cold hydraulic test pressure of 24 bar g. These figures define the equipment envelope; they must not be treated as permission to operate outside the pressure-temperature relationship shown in the original documentation.

Maximum differential pressure also changes with the specific gravity of the liquid. The documented maximum is 14.0 bar at specific gravities of 1.0, 0.9 and 0.8, 9.0 bar at 0.7, and 5.0 bar at the minimum listed specific gravity of 0.6. The minimum differential pressure is 0.1 bar. In practice, this means that a liquid lighter than water may reduce the available differential-pressure capability. A selection review should identify the drained liquid, its expected specific gravity, the pressure upstream of the trap and the pressure in the discharge line before choosing the arrangement.

Installation orientation and the balance-line question

Correct orientation is essential because the float must move freely. The installation guide directs that the trap is fitted below the item being drained and that the name-plate arrow points downwards. Screwed CA14 versions are fitted in the horizontal plane with the inlet at the top so that the float mechanism can rise and fall vertically. Flanged CA14 versions are likewise fitted in the horizontal plane so that the float mechanism moves vertically; the resulting flow direction is then left-to-right or right-to-left according to the selected version. Protective covers must be removed from all connections, and the materials, pressure and temperature limits must be verified against the intended installation before work begins.

A balance line deserves particular attention in air-system drainage. The CA14 has no air bleed, which allows it to hold gas back when the float is down. Under a low drainage load, air in the body can normally be displaced as liquid enters. Under a high drainage load, such as aftercooler or receiver drainage, air may not be displaced through the inlet pipe and the trap can become air locked. The guide states that a separate balance line is then needed and that it is routed back to the upstream side. Whether it is required can depend on the installation, but where there is doubt the documented preference is to use the balance-line arrangement. The diagram in the installation section shows representative drainage applications.

Using CA14 in a drainage system

Common applications include draining the foot of a rising pipe, a relay drain in a horizontal run, a separator on a compressed-air main and a small receiver. In each case, the objective is the same: remove liquid as it arrives while limiting unnecessary gas discharge. The detailed piping arrangement may differ. A receiver or cooler with a heavy intermittent liquid load has a different air-lock risk from a simple low point in a main. Downstream pressure, a safe discharge destination and the practical provision for isolation, venting and maintenance access should be established in the project design rather than improvised at installation.

After installation or maintenance, the system must be checked for correct operation and any alarms or protective devices tested. The CA14 operating principle does not require adjustment by the user: liquid lifts the float and opens the main valve; gas lowers the float and closes it. If the product is used at its maximum permitted conditions, exposed surfaces may be hot. Personnel should isolate and safely vent pressure, allow the product to cool, assess the contents and surrounding environment, use appropriate protective equipment and follow the site's permit-to-work requirements. The installation information below retains these safety requirements in document form.

Maintenance, spares and ordering confirmation

The CA14 is designed so that servicing can be carried out in the pipeline when suitable isolation has been provided. Before any work, pressure must be isolated and safely vented, and the product allowed to cool. The CA14 maintenance procedure identifies replacement of the main valve cone and replacement of the complete valve-and-float assembly. Joint faces must be clean, a new cover gasket is used during reassembly, cover bolts are tightened uniformly to the stated torque, and the isolating valve is opened slowly before checking for leaks. The full procedure, spare-part lists and recommended torques are preserved in the installation guide section.

The CA14 uses a Viton component. If a Viton-containing product has been exposed to temperatures approaching 315 °C or higher, the material may have decomposed and formed hydrofluoric acid. The technical information directs personnel to avoid skin contact and inhalation of fumes and to dispose of Viton in the recognised manner described by the installation instructions. This is a specific safety condition, not a routine disposal note.

For an order or enquiry, identify the CA14 model, the selected connection type and standard, the size, the intended fluid duty and the required direction of flow for a flanged version. State any certification or inspection requirement when the order is placed; material certification to EN 10204 2.2 is available according to the technical data sheet. The local price reference contains exact CA14 whole-product records for 1/2 in and 3/4 in sizes only. Check the full operating envelope, connection requirement and installation arrangement with the detailed technical and installation information before releasing a final specification.