What is the allowable height to freely drop concrete?

The allowable height to freely drop the concrete to avoid the segregate is not morethan a meter

the allowable height to freely drop not beyond 1meter 

Maximum allowable height of pouring concrete from the hose of boom is not more than 1 meter. 

According to the American concrete institute ACI article 301 concrete shouldn't free fall more than 3 to 5 feet in a single pour to avoid segregation about 90 to 150 centimeters .

It is better to drop concrete the as much close the pouring location but shall not be more than1 meter

1.5 meter to avoid segregation

As per ACI 301 its  3- to 5-foot limit.

Maximum allowable height for concrete casting (2)m

Thank you for the invitation

Agreed with colleagues