Need only alerts of hdd without mountpoints

i need to achive alerts from alertmanager for linux HDD

alertname = Host Out Of Diskspace
instance = xx.xx.xx.xx:9100
job = Webserver
severity = warning

only , but i got mount points alerts also with amost 163 alerts firing for single server
HDD alert , my alert rule is

- alert: HostOutOfDiskSpace
expr: (node_filesystem_avail_bytes * 100) / node_filesystem_size_bytes < 15 and ON (instance, device, mountpoint) node_filesystem_readonly == 0
for: 5m
severity: warning
summary: Host out of disk space (instance {{ $labels.instance }})
description: "Disk is almost full (< 15% left)\n VALUE = {{ $value }}\n LABELS = {{ $labels }}"

what else to be done in rule to avoid mountpoint alerts
attached the alert firing