Steap trap

Model Number

Steam Z

Structure of Steam Z

Standard model of Steam Z consists of three parts, which are body (Steam Z), Y Strainer and Ball Valve as shown in Fig. 1-6 below.

Steam Z has very simple structure. Its body is made of stainless steel and has a male screw at the inlet end of the body and a female screw at the outlet end. At the center of the inlet end a fine tunnel orifice is drilled. In the inside of the cylindrical hollow few orifice units, which are theoretically designed, are tightly fit so as to form an orifice train. This orifice train is specially developed to make the small capacity Steam Z free from choking by allowing Steam Z to adopt an orifice large enough to pass fine particles. The fixed mechanism of draining and the use of stainless steel material ensures the stable, trouble free operation of Steam Z almost permanently, making the maintenance work unnecessary.

Y Strainer has mesh installed inside and is to be installed between Steam Z and pipe. It prevents any alien particles from entering into orifice and keep orifice free from choking problem. Y Strainer is supposed to be provided as an integral part for Steam Z with small sized orifice. It is available as option for Steam Z of large capacity.

Ball Valve can be used for following purposes :

• remove the deposit on mesh inside Y Strainer,
  
• to drain condensate quickly
  
• to replace by-pass
  
• to check state of steam

Principles applied to Steam Z.

1) Orifice theory
Theoretical orifice means an orifice without thickness. Let?s call an orifice with sufficient thickness Tunnel Orifice. Those two are as shown Fig. 1-1, and 1-2 below respectively.

In the theoretical orifice, steam starts leaking at about 90% of load. When the drain generation rate is decreased from the capacity of 100 kg/hr, the leaking increases sharply along the curve shown in Fig 1-3, and finally reaches the maximum leakage 3.7kg/hr. In the tunnel orifice, steam does not leak until the load comes down at about 50%, then it also increases along the curve shown in Fig. 1-4. But the steam leakage is only 10%(0.37kg/hr) even at 25% load, which is by far smaller than the steam leakage used to drain off in conventional steam traps.

On passing through the tunnel orifice, steam and drain are not distinctively sectioned as shown in Fig. 1-5. If steam occupied the upper half and drain the lower half, the two would flow at different speed each other. But it is not the case as the steam and drain are mixed and flow in a turbulent state. In addition, the orifice is a fine tunnel, of which the drain will monopolize the entire cross section at some points, sealing the orifice in effect. As result, the steam can not rush through the orifice at the theoretically estimated speed. The sealing effect of the drain is so perfect in the range of 50~100% load that there is no actual steam leakage.

2) Labyrinth effect

The orifice train construction applied to the Steam Z causes the drain to undergo adiabatic expansion in the spaces between orifice units because the pressure in the spaces is reduced and some of the drain is converted into flush steam. These physical processes increase the resistance of the orifice and reduce steam leakage. This effect makes it possible to equip Steam Z with a large orifice, which renders Steam Z free from choking trouble with no increase in steam leakage.

Superiority of Steam Z

The performance of steam traps is judged by two factors. One is how swiftly condensate is drained without steam loss. The other is how long the steam trap maintains its original performance without maintenance work.

1) Minimized steam leakage

The steam loss of steam traps is mainly caused by following three reasons.

• use of steam for draining
  
• heat radiation
  
• deterioration of original performance of steam trap

Live steam is discharged together with condensate at the instance of beginning and end of draining. The leakage volume of live steam is different according to the working principles of each steam trap. So frequently, the volume is used to evaluate performance of a steam trap. The evaluation , however, should not be done simply with reference to initial performance as original performance of conventional steam traps with moving parts is deteriorated over time.

Conventional steam traps need steam to operate as moving parts consume a certain amount of steam. The used volume is different according to types of steam traps. By our analysis, it falls in the range of 1.2 ~ 9.17% of the draining capacity. But, Steam Z does not need any steam for mechanical operation as drain is done by the difference of pressure between the inlet and outlet sides.

2) Minimal level of steam loss by heat radiation

The amount of the loss is determined by the surface area, materials and thickness of a steam trap and weather conditions. If a steam trap is not heat insulated, steam is consumed on raining days twice as much as on sunny days. This means that heat insulation can cut steam loss by about half. However, most of conventional steam traps do not allow heat insulation because of their working principles. Even when heat insulation is possible, their complicated shapes make heat insulation ineffective. Also insulation sometimes cause maintenance problems. For those reasons, most steam traps are kept without heat insulation.

All models of Steam Z are of compact size. So the surface area is less than 50 cm2. This means heat radiation loss is very small even when no heat insulation is applied. Furthermore, pipes connected to Steam Z can be of smaller size than those for conventional steam traps. Steam Z also does not need by-pass pipe. Consequently, the total surface area for Steam Z can be reduced to one third of that for conventional steam traps.

3) No performance deterioration

All conventional steam traps, regardless of types or models, discharge condensate by on and off mechanism of a valve. This means that conventional steam trap is inherently susceptible to gradual increase of steam leakage over time. Damage of valve, scratch by foreign particles, corrosion of the valves, deterioration of the moving parts by fatigue, etc. cause insufficient sealing and increase steam leakage as time goes by.
On the other hand, Steam Z has no moving parts and is of simple structure with only a fine tunnel orifice passing through from one end to the other end. So Steam Z can keep original performance without maintenance work for long time and therefore has no steam leakage problem from deterioration of performance by passage of time.

Most steam traps operate in the pressure range lower than 20kg/cm2G which is low and medium pressure range. In this range, a huge number of steam traps are used in factories and plants, making perfect maintenance impractical, apart from the enormous amount of cost for such maintenance work.

4) No maintenance work

Steam Z has a long durability of almost permanence and as explained above, no performance deterioration is made over time. So maintenance work is not necessary for long time and therefore downtime for maintenance is minimized. Also, continuous draining makes sure of stable thermal efficiency of steam, which directly links to improvement of productivity of factories or plants

All these advantages demonstrate the superiority of Steam Z to all the other existing steam traps.

Comparison of Steam Z and Conventional steam traps

Item	Steam Z	Conventional steam traps
Working principle	Fixed orifice	on and off mechanism of valve
Durability	no moving parts, so trouble free	Moving parts are susceptible to break-down. Valve repeats open/close thousands of time per day.
Draining	Continuous draining	intermittent draining
Installation	simple and easy	complicated
Steam leakage	no	ever increase of leakage amount
Deterioration of performance	no	unavoidable as time goes by
Maintenance work	not required	regular maintenance is required
Heat transmission loss	minimal due to small surface area	Much loss due to large surface area
Air discharge	quickly done thru orifice	slowly done. Air vent is required for some cases.
Preparation for operation	not necessary	much time and steam is consumed
Water hammer	no	causes water hammer and is sensitive to impact of water hammer

What is the Steam-Z ?

The Steam Z is not a steam trap, but it is a condensate discharging device applying the character of an orifice. An orifice, open circular hole, has such a character that when mixture of steam (vapor phase) and condensate (liquid phase) flow through it, the flow rate of steam is much less than that of condensate. Applying this character in our patented Steam Z, we could remove all the moving parts from its design, making it extremely simple and compact structure. Moving parts have been the very reason to cause failure on all conventional steam traps. Failure of steam traps caused by moving parts is inevitable and has been regarded as inherent nature in conventional steam traps. Steam Z keeps steam system free from such failures of moving parts.

Advantages :

• Steam Z has no moving parts and continuously discharges condensate thru its fixed orifice, it can be semi-permanently used without any mechanical problem
• Initial performance is kept with very little maintenance work.
• There is no restriction for installing Steam Z in its direction. It may be set up vertically, horizontally or diagonally only if it is installed to same direction as condensate flows.
• Loss of efficiency and productivity for steam system can be minimized as Steam Z discharges condensates continuously.
• Installation work is quite simple as Steam Z is of small dimension and light weight.
• Steam Z does not cause water hammer problem and is strong against impact.
• Steam Z can be used for such cases as very large flow rate, high pressure, or very low pressure difference that has not been properly supported by conventional steam traps. For instance, Steam Z can be used for following cases.

1) 10MPa (100kgf/cm2) or higher inlet pressure with 1 ton/hr or more discharging capacity

2) 80 tons/hr or more discharge capacity

3) 0.002 MPa(0.02kgf/cm2) or lower pressure difference

Disadvantages :

• Selection of appropriate orifice size according to maximum condensate discharging rate is essential. So more accurate data are required to design a proper Steam Z. At least the maximum condensate discharging rate and the pressure difference between the inlet and the outlet should be available.
• As Steam Z discharges condensate directly into the outlet pipe, erosion occurs inevitably especially when much condensate flows. In order to lessen the erosion, installing a straight pipe of 10 times as long as diameter of the pipe at the outlet of Steam Z is recommended. This is not possible, then use of stainless steel pipe up to the first bend is recommended.