6 Operation Specifications of HTHP Dyeing Machine

The dyeing equipment employed under high temperatures and high pressure is known as an “HTHP dyeing machine.” There are some risks associated with using the HTHP dyeing machine. The safety concerns that must be taken into account when using it are briefly described below.

Opening and closing the cover

The steam valve must first be closed to stop the heat source once any high-temperature, high-pressure dying is complete. The pressure lowering valve must then be opened, and the lid can only be released when the pressure drop below 0 MPa and temperature drop below 85℃ inside the dyeing machine .
Under these circumstances, if the lid still won’t open, it’s best to check the instrument first to make sure it won’t break down and fail to accurately display the residual pressure. To avoid hazard, don’t forcefully open the cover.
Additionally, even though the fabric feeding machine is operating normally, if the temperature inside the machine has not yet reached 95 °C, do not close the pressure relief valve and attempt to allow the air inside the machine to exhaust outside. Particularly the semi-filled dyeing machine, since the machine’s saturated steam pressure typically begins to press when the temperature exceeds 99 °C. A virtual pressure will be created in the machine if the exhaust valve is closed too soon, and the color may also subtly shift. In addition, it will result in a “air wave” in the circulation pump, which will lead to fabric knots and blockages in the machine.

Exclude blocking cloth

If an HTHP dyeing machine is utilized incorrectly, there will be varying degrees of blocking phenomena, primarily for the following four reasons:

1. After the fabric enters the machine, it must move steadily and slowly for three to five minutes before the door is closed and the material is fed. Mechanical blockages can occur when mechanical devices, such as liquid return valves and nozzles, have not been modified owing to a change in processing types and the devices are eager to start.
2. After entering the machine, some light, thin, and high-density textiles, like Chun Yafang and polyester taffeta, float on the liquid’s surface rather than sink. The fabric can be kept from tying up and obstructing the cloth by using the full overflow filling method and the influence of the liquid return valve, heat exchanger, and filter screen. To reduce the likelihood of cloth knotting, degassing agents can be added to the dyebath to remove air from the fibers. In this situation, the right method should be developed based on the fabric type, and the right auxiliaries should be used to avoid failure.
3. The operator should continue to pay attention to monitoring the fabric’s operation in the dyeing machine after placing the fabric in the machine. When it is discovered that the operation is abnormal, the recoil blocking device should be turned on right away to fix the problem before it gets worse.
4. It is important to check to see if the foam in the dye bath increases after the fabric is fed into the machine. It is simple to produce inadequate foam suppression, leading to “air stroke” and blocking of the cloth, if the defoamer is not used or the amount is insufficient. So that the foam suppression effect is better, the defoamer should be added before the foam appears during dyeing.

​Refrain from doing any unauthorized actions on any machine part when the temperature is high

If the temperature in the dyeing machine surpasses 100 °C while the fabric is being dyed, pressure will be created inside the machine, and it should not be scrubbed with a damp towel. The glass will experience significant thermal expansion and contraction as a result of the temperature difference, which can cause cracking and serious accidents. The stop valves at the upper and lower ends of the water level glass tube should also be promptly closed when the liquor ratio is altered.

The other three operation specifications of HTHP Dyeing Machine can be seen here.