php中的BitConverter.ToUInt32？

In c# we have method BitConverter.ToUInt32. Which analog in php?

int _signLen = 8;
byte[] hash = MakeHash(value);
uint k = BitConverter.ToUInt32(hash, hash.Length - _signLen); //2908368849

I try make such, but its return null. Whats wrong?

$hash = $this->MakeHash($value);
$res = unpack("L", $hash,8); //null

$hash array contains

$hash = {array} [16]
 1 = {int} 102
 2 = {int} 41
 3 = {int} 156
 4 = {int} 64
 5 = {int} 54
 6 = {int} 101
 7 = {int} 223
 8 = {int} 38
 9 = {int} 209
 10 = {int} 47
 11 = {int} 90
 12 = {int} 173
 13 = {int} 60
 14 = {int} 141
 15 = {int} 126
 16 = {int} 108